MEGA65: VIC-IV alternate palettes on RRB

[smnjameson]

in NCM 16 color char mode alternate palettes can be selected by setting the BOLD + REVERSE attributes in the GOTOX marker. Note this relies on the extended attributes being disabled in bit5 of $d031 otherwise it will have no effect:

Expected:

Note how one of the moving balls is a different color

Xemu actual:

Test Files (Menu option B-D)
vic4tests.zip

[lgblgblgb]

So, it seems background also needs to use the "new" palette (the alternate palette) may be selected with GOTOXY. In fact as @smnjameson mentioned maybe everything from that point uses that palette (surely not sprites as those have separate palette optionally), not even restricted to NCM. Actually this is not too bad, I introduce the used_palette pointer which is initialized to the actual palette on each scanline start, but can be modified by the GOTOX token. Surely, renderers should use this used_palette then instead of the palette.

[lgblgblgb]

Edited issue name to better reflect it's not only for NCM

[lgblgblgb]

I consider this now as being done, since no more complains/bugs since them, I am aware of, at least.