Add a per-tick callback to Maxmod

It can be interesting to synchronize Maxmod with a different mod player that uses the PSG channels of the GBA. For that, the easiest thing to do is to add a new callback to Maxmod that gets called whenever the player handles one tick of the song. Currently, the event callback looks like this: ```c typedef mm_word (*mm_callback)(mm_word msg, mm_word param); ``` It would be fairly easy to add a new event that has as parameter value something like `layer << 0 | tick << 8 | row << 16 | pattern << 24`. Also, it would be good to improve the song error callback to provide the same information about tick, row and pattern: https://github.com/blocksds/maxmod/blob/7ebab72c8c857929209a37fdd8ccbfc74f3a8598/source/core/mas.c#L1586