Docs: Improve releasing notes
Docs: various cleanups doing release preperation
Translations: update from Pootle.locamotion.org
Docs: 2.5.1-rc1 release notes and related changes
Adjust minimum versions for required software

- Update minimum versions on requirements/*.txt
- Do the same in depcheck.py code
- Generate updated minimum requirements files (Still not sure why we have
  these)
Bump version to 2.5.1-rc1