fix uninitialised copy on 24bit colours
Merge pull request #100 from ailin-nemui/24bit-uninitialised

fix uninitialised copy on 24bit colours
restore the colour 0 ("black") that got broken by extended colours

the colour 0 was broken by the extended colours patch because it needs
an explicit bit check (lower bits will be false since it is 0)

Thanks to lhynes for the report
Merge pull request #110 from ailin-nemui/colour-break

restore the colour 0 ("black") that got broken by extended colours