This introduces datasette.io and datasette-dashboards to ddd.

Build Workboard Metrics with boardmetrics.py

See merge request releng/ddd!1

Change-Id: I1c1d5966d66fe2b8cd7900b4e7b9c81abe853587

Change-Id: I6ef1ee5e4f34e31996a86798a681c1430ca07a85

The output is suitable for generating a timeline with data points for each time a task enters or leaves a column.

The column_metrics data set looks like this:

| project_phid | column_phid | task_id | ts_begin (unix ts)       | ts_end (unix ts)      | duration (seconds)     |
|--------------|-------------|---------|--------------------------|-----------------------|------------------------|
| PHID-PROJ-1  | PHID-PCOL-1 | 123456  | Time task entered column | Time task left column | How long task remained |

We can also derive another type of metrics from this same dataset - to calculate global workboard metrics and task-specific
metrics we simply summarize the above data.

* Each task will have a duration value for each on the workboard.
** the lead time for the task is the duration in default colum
** cycle time is total off all durations except for default column
* Global workboard metrics are the mean of all durations in each column.
** We can calculate the metrics using a moving window in order to capture the change in metric performance over time.

Change-Id: Ie416494100b4833006bd974a758ab27e4c04a6b4

Moved trainblockers.py and boardmetrics.py into the ddd package
proper and made them importable for reuse outside the package.

Set up packaging so that we can publish the package to pypi.

Change-Id: I4001da1206c466d1575232601b57090fa77b5a1e

More or less complete usage example:

```py
        def process_transactions(transactions):
            mapper = PropertyMatcher()

            @mapper("transactionType=core:edge", "meta.edge:type=41")
            def edge(t):
                ''' match project edge transactions '''
                oldValue = [PHIDRef(p) for p in t["oldValue"]]
                newValue = [PHIDRef(p) for p in t["newValue"]]
                return [["projects", '', oldValue, newValue]]

            for taskid, t in transactions.result.items():
                st = sorted(t, key=itemgetter("dateCreated"))
                for record in st:
                    for row in mapper.run(record):
                        if row:
                            yield row

        transactions = get_some_transactions()

        for row in process_transactions(transactions):
            ''' do something with row '''
```

Change-Id: I6eac22574b02df75b9fd8c38d1a29856dd05f130

Sample output:

```
1.36.0-wmf.1   added         1
               comment       4
               resolved      1
1.36.0-wmf.10  added         6
               comment      11
               removed       2
               resolved      3
1.36.0-wmf.11  added         8
               comment      29
               invalid       1
               removed       4
               resolved      3
               stalled       1
1.36.0-wmf.12  added         2
               comment       4
               removed       1
               resolved      1
1.36.0-wmf.13  added         5
               comment      11
               removed       3
               resolved      4
1.36.0-wmf.14  added         5
               comment      11
               removed       4
               resolved      1
1.36.0-wmf.15  comment       3
1.36.0-wmf.16  added         9
               comment      15
               open          2
               removed       5
               resolved      5
1.36.0-wmf.17  comment       2
1.36.0-wmf.18  added         1
               comment      24
               removed       1
1.36.0-wmf.19  comment       3
1.36.0-wmf.2   added         7
               comment      27
               removed       7
               resolved      1
1.36.0-wmf.20  added         6
               comment      21
               declined      1
               removed       3
               resolved      3
1.36.0-wmf.21  added         2
               comment      12
               resolved      3
1.36.0-wmf.22  added         1
               comment       4
               removed       1
1.36.0-wmf.23  comment       3
1.36.0-wmf.24  comment       3
1.36.0-wmf.25  added         4
               comment      27
               removed       2
               resolved      4
1.36.0-wmf.26  added         4
               comment       4
               open          1
               resolved      6
1.36.0-wmf.27  added         5
               comment      12
               removed       2
               resolved      3
1.36.0-wmf.28  added         6
               comment      16
               removed       7
               resolved      2
1.36.0-wmf.29  added         5
               comment       8
               removed       4
               resolved      4
1.36.0-wmf.3   added         5
               comment      12
               removed       4
               resolved      1
1.36.0-wmf.30  added         5
               comment      13
               removed       1
               resolved      4
1.36.0-wmf.31  added         4
               comment       8
               removed       2
               resolved      2
1.36.0-wmf.32  added         2
               comment      17
               removed       2
1.36.0-wmf.33  added         2
               comment      15
               removed       2
1.36.0-wmf.34  added         6
               comment      19
               open          2
               removed       4
               resolved      4
1.36.0-wmf.35  added         7
               comment      10
               open          1
               removed       4
               resolved      5
1.36.0-wmf.36  added         9
               comment      33
               declined      1
               open          1
               removed       2
               resolved      7
1.36.0-wmf.37  added         9
               comment      39
               removed       8
               resolved      1
1.36.0-wmf.38  added         3
               comment       8
               removed       3
1.36.0-wmf.39  added         1
               resolved      1
1.36.0-wmf.4   added         3
               comment      11
               removed       2
               resolved      1
1.36.0-wmf.40  comment       1
1.36.0-wmf.5   comment      19
1.36.0-wmf.6   comment       5
1.36.0-wmf.7   added         1
               comment       1
               removed       1
1.36.0-wmf.8   added         2
               comment       7
               removed       1
               resolved      1
1.36.0-wmf.9   added         4
               comment      25
               open          2
               removed       2
               resolved      3
               stalled       1
1.37.0-wmf.1   added         2
```

Change-Id: Iadf025ef26e017376dcdc8aefff4a0e50651c34d