Lag Reduction in z2ft and Z2

[TheRealQuantam]

This comprises 2 features that are so closely linked they might as well go in a single PR:

1. Add a new flag for "Reduce lag" that applies various lag reduction techniques to make the game faster than vanilla Z2
2. When feature 1 is disabled and custom music is enabled apply part of the lag reduction to mitigate the extra lag caused by z2ft

Shouldn't take more than a couple days to implement as it's partially implemented.

Apparently targeting 4.4 beta 2.