massive mapper cleanupI pushed a lot of common behavior up to the Mapper base class, the most substantial of which is the bank-chunking logic. Doing so did lead me to yak-shave a bit, since I needed to add proper inheritence support to the Serialization library. It's not _completely_ transparent, but it's pretty good. Essentially, since C++ doesn't have a built-in "super" keyword to access the parent class, you have to manually specify the parent class. I didn't implement multiple-inheritence support though, since that isn't relevant to me right now. That said, the serialization library is really nifty, so (like I mentioned earlier) i'd like to spin it off into it's own repo. I also took this chance to add power_cycle() and reset() methods to the mapper interface, since I realized that some games would die on reset due to registers not being cleared properly. So yeah, feels gud man.