Add MBC30 mapper support

[theshillito]

Delta does not currently support the MBC30 mapper used originally only by the Japanese release of Pokémon Crystal but has since been used by ROM hacks to access additional memory.

There is some technical information and a test ROM here https://gist.github.com/ZoomTen/1161fb269cd012a2b927560e3290a9f4

And here is a screenshot taken when launching Pokémon Crystal Clear when it detects that the mapper isn't supported.

And running the test ROM in delta I can confirm MBC3 support but not MBC30