Move from SparseArray to TIntObjectMap

Also, refactor optimizers in prep for rewrite
Refactor test package to match main package
Remove SparseArray

Good bye SparseArray. We had some good times together and I will
always cherish those. But it's best for both of us if we separate.
You keep on being a nifty little way of mapping primitive ints to
objects. I'm moving to Trove now, and I hope you understand. The
benchmarks aren't everything, but damn, they're way better for
my use cases. And let's not forget your silly keyAt stuff. But
I'm rambling. Point is, I want you to be happy. You're a good
data structure, and I mean that. Take care.