use unifont and add support for wide-characters and combining glyphs

use unifont and add support for wide-characters and combining glyphs

this patch makes use of unifont with genfont2 and introduces support for
wide-characters and combining glyphs

for this we have to save the width and possible diacritic in the
textcell, which means we also have to reset them properly and give those
values also to draw_char_at

to determine the width we use the wcwidth provided by unifont
(because in unifont some characters are wide which normally are not)

we mmap the generated fontfile, and drop the glyphs.h, which reduces
the initial memory use, and shares the pages between processes

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>