js: refactor and simplify @mentions handling - no functional changes The autocompleteCreate and get_mention functions are inlined. The mentionQuery and tuple in datasource are replaced with before/search/after data attributes on the $container element. Variable use is simplified - less variables, better naming, and better content. The @ is now in the before string, not in the search string.

[pytest]
# only look for tests in kallithea/tests
python_files = kallithea/tests/**/test_*.py
addopts =
    # --verbose
    # show extra test summary info as specified by chars (f)ailed, (E)error, (s)skipped, (x)failed, (X)passed, (w)warnings.
    -rfEsxXw
    # Shorter scrollbacks; less stuff to scroll through
    --tb=short