Some work on defining blaze functions
Construct typed expression graph from applied blaze kernels
Some cleanup
Some work on expression graph and visualization
Start on blaze AIR

	- mapping from expression graph to AIR
	- explicit conversions
	- external uses annotation
Preliminary AIR interpreter
Some work on AIR
Some AIR tests and proper conversion insertion
Test expression graph
Add evalution strategy context manager
Work on blaze.eval
Add simple AIR pipeline and interpretation prepare function
Working python interpreter with NumPy backend (for testing/debugging)
Better separation of deferred graph construction and the overloaded blaze Kernel
Clean up some deferred metadata tracking
Fix evaluation strategy reference
Add JIT interpreter using KernelTree
Implement Deferred data descriptor, remove DeferredArray
Make sure dshape and typeof always return a DataShape
Add __array__ on data descriptors