[Customdrawn] New fast bitmap copying

[Felipe Monteiro de Carvalho]

Hello,

http://svn.freepascal.org/cgi-bin/viewvc.cgi?view=rev&root=lazarus&revision=36576

This commit starts speeding up image drawing. The magnifier full
painting went from 630ms to 477ms for me.

ToDos:

1>Give up on speed improvements if there is a non-ractangular clip region
2>Consider the clip region
3>Implement for 16 and 32 bpp too, is now only for 24 bpp (like our
X11 implementation is)
4>Consider if we are not getting out of the destination size in the X axis

-- 
Felipe Monteiro de Carvalho