Fixes #313

Currently translated at 36.5% (321 of 880)

Fixes #341.

Currently translated at 28.0% (246 of 880)

This way we link based on the content rather than message ID which does
not have to be unique for a project.

Fixes #326

Issue #326

This will be used for linking instead of checksum (issue #326).

Currently translated at 27.7% (244 of 880)

Currently translated at 27.4% (241 of 880)

Fixes #315.