Retro8 does not allow blank newlines in carts
Example cart: [A Doukutsu Demake.p8.txt](https://github.com/Jakz/retro8/files/4148106/A.Doukutsu.Demake.p8.txt)

This cart has a newline between the `__gfx__` section and the `__gff__` section, which cause an assert to fail, instead of just skipping the line like PICO-8 does
