Support fractional-scale-v1

This make text less blurry. It continues to works without.

before:
https://dav.missbanal.net/00bd0fd5-e22f-4a60-87f8-ce6f400d33c9.png

after:
https://dav.missbanal.net/a3f02f1e-d6ce-4378-a141-e2093ba87eed.png
Signed-off-by: Willow Barraco <contact@willowbarraco.fr>
Signed-off-by: Maarten van Gompel <proycon@anaproy.nl>

keyboard.h

@@ -95,7 +95,8 @@ struct kbd {
 
 	bool print;
 	bool print_intersect;
-	uint32_t w, h, scale;
+	uint32_t w, h;
+	double scale;
 	bool landscape;
 	uint8_t mods;
 	uint8_t compose;