Bugfix: glitches at the top of the scrolling starfield

Hi everyone,

Here is a small but important bugfix release to Galactor.

There was glitches that were appearing on top of the scrolling starfield, right below the score. I had noticed them during the Jam, but failed to
fix this issue. It was fixed a day ago by an expert NES developer named Fiskbit over the NesDev forums:
https://forums.nesdev.org/viewtopic.php?p=304756#p304756

Not only did he narrow down the source of this issue, but he also managed to provide a working fix for it!

For those interested in the technical reason, it was due to a bad timing of the scrolling register writes during the active frame.

Indeed, you can see that the score, drawn with background, is static, while the starfield, also drawn with background, is scrolling. This X/Y background split is made with a technique called "sprite 0 hit split scrolling", like Super Mario Bros. and countless other games did. Modifying the scrolling position of the only background layer of the NES hardware while it is drawn onscreen is tricky. It requires precises timing to avoid issues, like the glitches my game had before. The bug was actually present in the NesDoug library that this game uses, so it's the NesDoug library source code that was fixed here by Fiskbit.

I've updated the game ROM and source code zip with fixed files, so you'll no longer encounter this issue while playing.

A huge thank you to Fiskbit for fixing this issue, and explaining me in great details what caused it and how he fixed it.
It's another proof of how awesome and helpful the NES homebrew scene is :)!