Addshore authored Apr 25, 2021 and Addshore committed May 12, 2021

Various changes have been happening but the README is not totally up to date.
So update it!

And also add a ./dev.sh script which is now the recommended way to run the
tool in its un-built fashion.
This takes care of making sure that the static files are rebuild every time
you run the script, as this as tripped me over quite a few times during rapid
development.

Another alternative would be to force people to build each time, but IMO
we shouldn't force this as it just ends up being slower.

Change-Id: I6cbd916086c5177d5c0f98a03659e6d5d06ba467