alpha.v2

Second alpha release!

Main changes:

• now we have a logo for klo-gba.js! Thank you very much @Kniksisk 💙 (#38, #40)
• add eraser tool; now is more intuitive to clean a tile, just use the eraser! (#43)
• add vision 1-3; let's paint it! (#45)

Minor changes:

• show error if trying to load a non supported rom region (#41)
• fix default filename extension when is saving the custom rom (#42)
• fix vision selector when none vision is selected (#44)
• many refactors on all codebase (#37, #39)