front-end: Move .less files to the front-end folder The less directory was public - we prefer to have the source file outside the public folder. And we prefer to name the folder after the use of content instead of the primary file type of content. The last remaining 3rd-party file, mergely.css, was still not used from that location and is just removed.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.