This splits the Sphinx tag option from SPHINXOPTS. This allows us to
specify the tag without having to remember to add -W and -t. It also
fixes not being able to specify the tag with make.bat on Windows.
While we are touching this, redundant SOURCEDIR uses are removed (main
is already the default) and the .github/workflows/publish-ide-docs.yml
script is fixed (ide directory no longer exists).
With EV3 dropped from the 3.X documentation, the main docs are now nearly identical to the IDE docs, save for some layout changes.
Having just one set of docs is easier to maintain. This drops the IDE doc target.
David Lechner
Laurens Valk