TakingBroadcastSeriously

This package implements a hack around broadcast fusion for custom array types. See the tests for example usage. You need to:

1. Call unfuse(ArrayType) to intercept broadcast calls.
2. Make sure any function you want to use inside broadcast is on the list here.
3. Overload broadcast_(f, xs...) for your array type.
4. Cross your fingers and hope this holds up for the next six months.