Use suggestion author for storing authorship
Translated using Weblate (Japanese)

Currently translated at 57.5% (458 of 797)
Merge remote-tracking branch 'origin/master'
Differentiate suggestion acceptance from translation

Accepting suggestion now has different entry in changes database.
Missing import
One place for imports
Revert "One place for imports"

This reverts commit ce1fdc8523f6d166a2eb0cd0b9e3f35ce4bb1be3.
Prevent double imports
Correctly store source string changes

With monolingual files, source string can change without changing
checksum, we need to properly detect this and update unit if needed.

See also issue #118
Remember previous source string for monolingual files

On source string change (and if format does not expose this on it's
own), we store current string as previous string, so that translators
can see what has been changed (see issue #118).
Set fuzzy flag for monolingual files

On source string, we want to set fuzzy flag as well (issue #118).
Flags persistence for monolingual files

We need to keep fuzzy flag and previous source string over unit updates
if translation has not changed (user can still manually unflag unit as
fuzzy). Fixes #118
Fix typo
Update po files
Translated using Weblate (Greek)

Currently translated at 100.0% (798 of 798)
Translated using Weblate (Czech)

Currently translated at 100.0% (798 of 798)
Translated using Weblate (Slovenian)

Currently translated at 100.0% (798 of 798)
Translated using Weblate (Turkish)

Currently translated at 100.0% (798 of 798)
Include header in CSV exports

This allows translate-toolkit to automatically detect file and makes
import work (issue #256).
Add test for csv and po import to dictionary (fixes #256).