feature: define animation frame

[jjhesk]

#48
#67 #30
just check if there are any script to make definitions for this type of spritesheet.

for dealing a sprite with 3 x 4 / 32x32 px boxes

[piratesephiroth]

you could split it into separate images with imagemagick
magick convert -crop 32x32 spritesheet.png part.png

you can merge 12 32x32 images like that into that spritesheet
magick montage part*.png -tile 3x4 -background #00000000 -geometry 32x32 spritesheet.png