#1635 Modify some UI strings

[Jean-Christophe Helary]

I proposed that we change a few UI strings to make the overall experience less "textual".

The discussion is here:
https://sourceforge.net/p/omegat/mailman/omegat-users/thread/71F744C7-9189-4F19-A418-683E98A94DAD%40traduction-libre.org/#msg37715601

We have not yet reached a conclusion.

[Jean-Christophe Helary]

Plenty of work has been done on the UI for the 5.8 release:
https://github.com/omegat-org/omegat/pull/348
https://github.com/omegat-org/omegat/pull/350
https://github.com/omegat-org/omegat/pull/347
https://github.com/omegat-org/omegat/pull/346
https://github.com/omegat-org/omegat/pull/330
https://github.com/omegat-org/omegat/pull/305