Refactor and additional features

[handsomematt]

Requires changes in flashcart_core to be incorporated too: https://github.com/kitling/flashcart_core/pull/43

Quite a few changes, you can view in detail in the git commits, summary however:

• Huge code refactor, move code neatly into folders, move flashcart_core into main directoy, move UI stuff into seperate stuff, etc..
• Instead of auto detection, show a list of flashcarts to select from. User selection is still verified, but per flashcart implementation. As previously discussed this is better then running cart commands aimlessly trying to guess what cart it is. Sometimes this isn't possible and sometimes other cart commands have undesired effects.
• Use the flashcart_core device implementation from: https://github.com/kitling/flashcart_core/pull/43
• Improve cart initalization, read the header and cart id and cart reset functionality. (Still todo is pass the commands properly)
• Warning prompt before starting.
• Show version information passed via the makefile to C using git describe - should allow us to debug user problems easier.
• platform.cpp for platform specific methods from flashcart_core.