gfxlib2: Make color setting helpers for fb_GfxPalette*() functions public

in preparation for following commits.
gfxlib2: Split fb_GfxPaletteUsing() into separate module

fb_GfxPalette() is always included because it's used from gfx_screen.c,
but fb_GfxPaletteUsing() can be in a separate module so that it's only
included when actually used.
gfxlib2: Add fb_GfxPaletteUsing64(), LONGINT version of fb_GfxPaletteUsing()
gfxlib2: Split fb_GfxPaletteGetUsing() into separate module

(allowing it to be only included when needed)
gfxlib2: Add fb_GfxPaletteGet64(), LONGINT version of fb_GfxPaletteGet()
gfxlib2: Add fb_GfxPaletteGetUsing64(), LONGINT version of fb_GfxPaletteGetUsing()
rtlib: Split hook_mouse.c module in two

(in preparation for the next commit)
rtlib: Add LONGINT overload for getmouse()
gfxlib2: Add LONGINT overload for getjoystick()
gfxlib2: Add LONGINT overload for screeninfo()
rtlib: Add LONGINT overload for dir( outattrib )
rtlib: Add LONGINT overload for dir( filespec, attrib, outattrib )
tests: Fix more unnecessary warnings in SWAP test, see also fc347435
tests: Fix pointer casting test for 64bit
Adjust "param list too big" check to depend on pointer size

so it allows more on 64bit. The check for UDT parameters was already based
on the pointer size too, so this seems right.