Explain game bonuses

[Fippe94]

Add an ingame explanation for the extra bonuses you can get after winning a game. The best way would probably be to add a mouseover text for each bonus so you can see on the end screen what you did.

[Chapuz]

+1 on this

About bonuses, there is a bonus for unupgraded decks I see? o.o

[serprex]

https://github.com/serprex/openEtG/commit/f1ee697958a993ce6d87daa0b19122f3990d1466