enhance pragma to support single point copy (#863)

* modified schedule_dataflow_rewrite.cc to fix losing tensor problem

* modified schedule_dataflow_rewrite.cc for lint scan

* modified schedule_dataflow_rewrite.cc for lint scan

* using tensor's value_index to index output of stage op

* repare address offset for different kinds of dtype

* bc

* aaa

* aaaaa

* repare address for different dtypes

* remove nonsense files

* add whitespace of line 581

* use base alloc elem_type

* enhance the testcast of basic buffer is 64bits,32bits,16bits,8bits

* use extends[0]->type() as dtype of offset

* clear program writes

* enhance inject_copy_intin to support of pragma stmt with no loops

* fix cpplint errors

* fix cpplint error of !

* enhance detectLinearEquation to support with no loop vars

* fix cpplint errors