A few small bugs

[radioheadguy]

Noticed a few small bugs:

1. When applying an overlay in GBA games (mgba), the displayed game would shrink and cut off around 5% around the outside - the width is integer scaled so not sure why it’s happening
2. When applying an offset filter in GBA (mgba), it shows a white line at the bottom
3. pico8 native (with licensed files) only opens in integer scaling - would be great to have a full screen option. Twigui has fill screen as a “core” option, something similar would be great!