Spring cleaning in the strings to be translated?

[jaz-on]

Hey @pfefferle,
While working on the French translation, I noticed that many strings are not actually used.
I could be wrong, but keeping a limited list might motivate more translators to translate the plugin into their language.

Currently, some strings are particularly complex to translate. Some are almost a paragraph long... :/

[jaz-on]

Nevermind I was looking at the readme strings... ><'
I translated a good part of the stable branch already, depending on my GTEs feedback I could then become an official editor for the French translation of the plugin.