extensions: use context manger for open()

py3: open extension source in binary mode to read docstring as bytes

grep: adds allfiles mode Adds an allfiles flag that lets you grep on all files in the revision and not just the one that were modified in that changeset. This would work on a single revision and get all the files that were there in that revision. So it's like grepping on a previous state. Using this with wdir() :: `hg grep -r "wdir()" --allfiles` is what the default behavior is desired for grep. Support for multiple revisions to be added later. Differential Revision: https://phab.mercurial-scm.org/D3728

morestatus: remove some extra spaces The information about unfinished states in `hg status -v` had a lot of spaces which are not required and feels weird. Let's limit the spacing to four spaces. Differential Revision: https://phab.mercurial-scm.org/D3730

graph: improve graph output by using Unicode characters This extension beautifies log -G output by using Unicode characters. A terminal with UTF-8 support and a monospace Unicode font are required. Differential Revision: https://phab.mercurial-scm.org/D3665

py3: whitelist another 5 passing tests thanks to the ratchet Differential Revision: https://phab.mercurial-scm.org/D3762

shelve: wider check for successful abort in test The test was previously focusing on checking that the "sub-rebase" aborted properly. Since rebase is an implementation details we should also check for other messages. Differential Revision: https://phab.mercurial-scm.org/D3686

shelve: use full hash in tests Using revision number is fragile. Moving to full hash to help with further development. Differential Revision: https://phab.mercurial-scm.org/D3685