Add 0x00407074 and also clean up mouse structs/addresses

I've decompiled the other side (mouse input reading), and clean up a bit.

I still don't get fully what is going on in 006E83C7 (game_get_next_input) because the ASM is more detailed that the C, but I assume that is just due to some refactoring? Regardless, assuming that is correct 407074 should be fine