We're switching to TrueColor now, and maintaining a 65536 entry palette
for the various palettized bits.  This change hurts the overlay output most
since it currently means floating point calculations for every pixel.

The getfont() function now takes a fontnum argument so you can get all the
current fonts.

The vmem array now holds the font data, so once a glyph is written to the
screen, it can stay in that font "forever".  This still has some issues
with savescreen()/restorescreen() since there's no extension to grab the new
stuff... that'll be coming soon, likely replacing the pgettext() and
pputtext() functions.  For now, various popups will likely reset fonts to
the default font on the screen.

Now that we have all this, the status bar in SyncTERM can retain the default
font and colours at all times.  Further, menus can be displayed in the "right"
colours and fonts, and no more translation will be needed.  This is a work
in progress though, so there's likely to be glitches.  The scrollback doesn't
have the font data either (same issue as savescreen()/restorescreen()).