Add Breton French keyboard

[zeecho]

This is based on FRThumbKeyV2
Here are the main differences :

• adding some characters used in the Breton language: ñ, ch, c'h and ꝃ (the last one is not so common anymore but still interesting to have as it has strong ties with the Breton language)
• adding " because I think it's often more useful than the guillemets
• moving z in order to have a spot for ñ

My main concern is for the letters using several characters (ch and c'h) (yes, they are considered to be only "one letter" in Breton, hence why I added them). Will they be displayed correctly? Will they be typed correctly?

[dessalines]

Yep, they should be rendered okay.