Currently translated at 7.0% (69 of 974)

Fixes #423

Currently translated at 0% (0 of 0)

Created new translation.

Currently translated at 100.0% (13 of 13)

Currently translated at 0% (0 of 0)

Created new translation.

Issue #375

Give users more information why the quality check has fired and why it
is important to fix this problem.

Fixes #417

Currently translated at 100.0% (974 of 974)

There is a special rule when the translation is empty, it is treated to
be same as source string.

Fixes #420

Fixes #418

Currently translated at 98.9% (963 of 973)

This gives user better visual feedback what went wrong.

- load once we're getting close to bottom of page to prevent user
  waiting for units
- prevent multiple loads at one point