Fix rendered characters have been chipped for some TrueType fonts

ImageFont ignores descender value of TrueType fonts (uses ascender only),
then some fonts which use descender is chipped on rendering.
Fix tests which are hardcoded for little-endian CPUs
Make quantization code more portable
Merge pull request #178 from manisandro/endian

Fix tests which are hardcoded for little-endian CPUs
create a palette before converting transparent L-Mode to RGBA
fixes #154
Merge pull request #179 from manisandro/quantization

Make quantization code more portable
Merge pull request #45 from tk0miya/fix-rendered-chars-have-been-chipped

Fix rendered characters have been chipped for some TrueType fonts
Merge pull request #180 from d-schmidt/master

create a palette before converting transparent L-mode to RGBA
Merge branch 'master' of https://github.com/python-imaging/Pillow