Include and tiles

[Cyrille Berger]

Hi,

As far as I have understand the wishes of our mighty maintenair, we want to 
bury the tiles stuff and hide from our API. But, some crucial headers file 
(kis_paint_device.h) require tiles headers, so the question :
- install some tiles headers, but not documenting them and marking them as 
internal
- rework the headers file (probably moving implementations to the .cc) to 
remove the tiles headers requirement

-- 
--- Cyrille Berger ---