tests/test-backwards-remove

localrepo: remove 'closed' argument to heads(...) function

- repository heads are not associated with the closed attribute, so
remove it making the code in line with the concept.
- Fix functions that were calling heads with the parameter.
- Adjust webcommands.branches to include the concept of inactive
as well as open and closed branches
- Fix code and docstrings in commands to make the correct use of
closed branches & branch heads clearer
- Improve grammar of 'hg heads' help text (2nd submission)

this does not alter the cli for hg branches, that work is
still to be done

#!/bin/sh
hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
ls
echo This is file b1 > b
hg add b
hg commit -m "commit #1" -d "1000000 0"
hg co 0
# B should disappear
ls