combined {fg,bg}Is24bit and alternate{Fore,Back}groundSemantics into {fore,back}groundColorMode
removed 24-bit color from CURSOR_BOX
logic fix
added 24-bit color to underline
style fixes
type changes
_drawCharacter:alternateSemantics -> _drawCharacter:fgColorMode
readded attribute tests to ForegroundColorsEqual
touch up comments
*colorForCode now handle 24-bit case
added 24-bit color support to _drawCharacter
extra credit :)
Merge fixes from branch '24-bit-color'