Added generic search-by-compare function to icon cache

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Removed font cache from predef header

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
[cleanup] split icon cache into abstract icon cache and icon_map

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>