tests: add tests for hgweb to test-keyword

Merge main and crew.

removed trailing spaces

ui: disallow newlines in usernames (issue1034)

update: no -C needed to switch branches without outstanding changes

coverage: deal with symlinked input paths (MacOSX issue) /tmp is symlinked in MacOSX therefore test scripts as well as python modules are installed in a symlinked location. coverage.py uses abspath() to normalize its inputs which fails if these are referencing real paths. Use realpath() instead.

Make churn an official extension

tiny tab cleanup

improved semantics for remove (issue438) - Added files are never deleted (only removed with --force). - Modified files can only be removed with --force. - With --after, only deleted files are removed. - With --after --force, all files are removed but not deleted.

test: fix mixing exec bit on test-hgwebdirsym