Put project-related URL generation in a mixin

This will allow further reuse when incorporating virtual project
resources.

Pick notes: Minor conflicts due to code divergence.

Conflicts:
	pootle/apps/pootle_project/models.py
Added support for cross-language resources

This allows working at the project level for individual files and folders:
seeing the overall progress as well as translating and accessing the
export view.

Fixes evernote/pootle#75.

Pick notes: Fixed several conflicts due to code divergence.

Conflicts:
	pootle/apps/pootle_project/models.py
	pootle/apps/pootle_project/urls.py
	pootle/apps/pootle_project/views.py
	pootle/core/decorators.py
	pootle/templates/projects/_tabs.html
Also account body padding as part of the sidebar height
Also set line-height
These situations are handled by the buttons themselves
Format drop-down files and directories

Fixes evernote/pootle#80.

Conflicts:
	pootle/static/css/style.css
Don't retain the resource when the project changed
Global warming warning
Simplify the disabled color state by the means of SVG filters (tested in Chrome and FF)
More button styling adjustments
Use a better default message for file dropdown, since the old one actually introduces a new UI concept called 'Resources', which is not used anywhere else
Improve file breadcrumb dropdown rendering
Highlight match results in a custom formatted list item
Highlight search results in a more prominent manner
Show mute/unmute records in timeline

Pick notes: Fixed minor conflicts.

Conflicts:
	pootle/apps/pootle_statistics/models.py
	pootle/apps/pootle_store/views.py
Cleanup: Do not mark blank string as translatable
Cleanup: coding style fixes
The pattern now expects more arguments
Much faster approach to retrieve project's resource paths

Part of evernote/pootle#79.

Note picked from Julen's commit in GitHub:

    I should have written this in the commit message/issue, but I'll mention
    it here for the record (better late than never): the ugly replace/concat
    functions are necessary because at the DB level Pootle doesn't have the
    notion of paths relative to TPs.

    With the conversion function, pootle_paths such as
    /<lang-code>/<project-code>/path/to/file.po become path/to/file.po.
    This way it's possible to select unique occurrences of these relative
    paths.

Pick notes: Had to fix a conflict because of some syntax changes we did
    to support PostgreSQL in 8a325b1b.

Conflicts:
	pootle/apps/pootle_project/models.py
Provide raw SQL alternative for PostgreSQL

This is the "magic" of using raw SQL.