* prefetch interface added
* prefetch python comments modified. prefetch info data structure maintained.
* start injecting prefetches. first step (domain touch) implemented.
* domain touch tested.
* Prefetch ir_mutator and ir_visitor dispatch registered.
* modify domain touched from passing a func_ref to passing a tensor
* modify domain touched from passing a func_ref to passing a tensor
* modify Tensor copy to Tensor ref
* temp commit for rebase
* debug info removed, typo fixed, ready to rebase
* prefetch flatten test add!
* roll back builtin functions to side effect functions
* lint error fixed!
* add cache line size to storage flatten argument
* forgot modifications add
* change code style to dmlc-like; get rid of can_prove, use manually compute instead
* python lint error fixed
* modify instrinsic name to pass tests
* [TEST] get rid of str(), replace them by accessing attributes
* change map to list comprehension
* redundant numpy import removed
