Update Greek translation

[gmou3]

A few translations get messed up from time to time.

There also exist some places where the UI remains in English for me.

In the library viewer:

• All Books
• Add Catalog...
• Library Menu (hover)

In the book viewer:

• Pin Sidebar (hover)
• Scrolled Mode (book's main menu)
• Reduce Animation (inside a book's font menu, under behavior)
• Copy Identifier (pop-up after choosing text)

[johnfactotum]

They don't work because of the #, fuzzy line, which means that the translation was automatically generated by gettext. So one should remove that line from entries where the translation has been resolved by a translator.

[gmou3]

Thanks, fixed!