Unbreak run-tests support for out-of-tree extensions

Merge with crew-stable

Some platforms lack the PATH_MAX definition (eg. GNU/Hurd). Thanks to ronny for making it cleaner.

test-fncache: Use find instead of ls -R. Different platforms implement -R differently (and it produces unneccessarily verbose output in this case). find is just as good and more consistent. Unbreaks test on OpenBSD. Edited by pmezard: added 'sort' call

Make test-verify SUSv3 compatible. 'head -c' isn't supported on (at least) OpenBSD and is not part of SUSv3. Instead, use dd. See also: http://www.opengroup.org/onlinepubs/009695399/utilities/head.html

Support branch names in contrib/bash_completion Anywhere a revision is needed a branch name can be used to specify the tip of that branch, so branch names should be tab completed.

Support merge in contrib/bash_completion

context: add a dirty method to detect modified contexts

dirstate: don't complain about 0-length files

commit: move some setup outside the lock

Add cp950 as problematic encoding which is used in chinese windows.

hgweb: allow distinction between open/closed branches on branches page

commit: rename wctx to cctx

mq: fix commit prototype

commit: trade O(n^2) file checks for O(n^2) dir checks

commit: move explicit file checking into repo.commit

dirstate: more accurate use of match.dir callback

commit: editor reads file lists from provided context

commit: drop the now-unused files parameter

tag: use match.exact for commit

commands: drop files arg for commit calls

transplant: use match object rather than files for commit

rebase: remove unneeded status call before commit

gpg: use match.exact rather than files for commit

mq: drop unneeded files args for commit

commit: apply force flag without files

fetch: no need to pass files list to commit

templater: retain author's full name if no email is supplied (issue1685)