Establish BSD license
add NSF grant info to README
ENH: add cross_join operation
add argmin/argmax example
improve slicing/subarray operation
add single-element access
add a check for sparse->dense conversion
make join ops work on single array
join ops: implement radd, rsub, etc.
add broadcasting functionality
add validation in join_ops
implement axes argument in transpose
BUG: fix broadcasting shapes
ENH: add reshape, linspace, arange