templates: more consistently put icons inside 'Delete' and 'Edit' buttons - on repo, repo group, user and user group list page. For now, we keep the text and keep the button visible. The Edit button was typically a submit button, not inside a form but inside an <a>. It did thus not really trigger a submit but just followed the link. Extracted by Mads Kiilerich.

# 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
.