Imported some of the GPLv3'd changes from RhodeCode v2.2.5.

This imports changes between changesets 21af6c4eab3d and 6177597791c2 in
RhodeCode's original repository, including only changes to Python files and HTML.

RhodeCode clearly licensed its changes to these files under GPLv3
in their /LICENSE file, which states the following:
The Python code and integrated HTML are licensed under the GPLv3 license.

(See:
https://code.rhodecode.com/rhodecode/files/v2.2.5/LICENSE
or
http://web.archive.org/web/20140512193334/https://code.rhodecode.com/rhodecode/files/f3b123159901f15426d18e3dc395e8369f70ebe0/LICENSE
for an online copy of that LICENSE file)

Conservancy reviewed these changes and confirmed that they can be licensed as
a whole to the Kallithea project under GPLv3-only.

While some of the contents committed herein are clearly licensed
GPLv3-or-later, on the whole we must assume the are GPLv3-only, since the
statement above from RhodeCode indicates that they intend GPLv3-only as their
license, per GPLv3§14 and other relevant sections of GPLv3.

diff parser: redefined operations stats for changes

- don't loose info about multiple operations like rename + chmod
- new Binary flag when dealing with binary file operations
- fixed diffs after mercurial 2.6 when GIT binary diffs were fixed
- added more tests for multiple operations

- refactored the way diffprocessor returns data. It's
now easier to extract type of operation on binary files
- diffprocessor doesn't append that information into the diff itself

diff: don't link to removed files

It is 'D' for removed, not 'removed'.

diff_block: fix link to file revisions

Pull requests would link to file revisions in the wrong repo. That was
obviously only visible when merging between different repos - but then it would
link to a non-existing revision.

diff_block is apparently used pull-request-style with the 'b' revision of the
diff shown first. It thus also has to point at the 'other' repo which is where
the other revision can be found.

new patch function, and urls schema.
now rhodecode generates
- diff
- plain diff
- patch files

both for git and hg

Implemented generation of changesets based
on whole diff instead of per file diff. That
can give a big speed improvement for large changesets in
repositories with large history.
- improved handling of binary files
- show renames of binary files
- implemented new diff limit functionality
- unify diff generation between hg and git
- Added binary indicators for changed files,
- added diff lib tests

Added h.tooltip to all places that tooltip_title is used.
- improved escaping of < and > inside tooltips

added hidden fulldiff GET param for disabling big diff cut off limit.
fixed context toggle options on single file diff

UI fixes
- added expandable commits messages
- ui fixes, icons/graph

implements #308 rewrote diffs to enable displaying full diff on each file
- fixed escaping of html special chars in file editor

code garden for changeset ranges and comments
- disabled (for now) comments on changeset ranges
- code reuse by mako namespaces
- added flag for enabling comments in diffs