Add 1bpp and 8x16 for DMG/CGB

[basxto]

This implements 1bpp (half 2bpp) and 8x16 (used in sprites) for original Game Boy and Game Boy Color.

Implements #25

1bpp is not supported by the hardware, but easily realized with software, it's just

ld a, (hl+)
ld (de), a
ld (de), a
inc de

Tested with

#!/bin/sh
sfc=../bin/superfamiconv
testfile=cgb_dmg_testpattern.png
echo === 1bpp
${sfc} tiles -v -Mgb --no-remap -B 1 -i ${testfile} -d ${testfile}.1bpp -o ${testfile}.1bpp.png
echo === 1bpp
${sfc} tiles -v -Mgb --no-remap -B 1 -i cgb_dmg_testpattern_mono.png -d ${testfile}_mono.1bpp -o ${testfile}_mono.1bpp.png
echo === 2bpp
${sfc} tiles -v -Mgb --no-remap -i ${testfile} -d ${testfile}.2bpp -o ${testfile}.2bpp.png
echo === sprite
${sfc} tiles -v -Mgb --no-remap --sprite-mode -i ${testfile} -d ${testfile}.spr.2bpp -o ${testfile}.spr.2bpp.png
echo === 8x16
${sfc} tiles -v -Mgb --no-remap -H 16 -i ${testfile} -d ${testfile}.16.2bpp -o ${testfile}.16.2bpp.png

and

[Optiroc]

Thanks! Looks good 👌