split into datasets

review fix

fix merge issues

fixed minddata lite build issues

1. Check if data_ is null before compare it;
2. Always allocate an array for data_ even if size is zero.

commit 2

lint fix

lint fix 2

updated backprop + st test

test_file_fix

test_file_fix_2

fixed header_guards

comments addressed

clangFormatFix

if AbstractFunction comparison succeed in NewContext, then the evaluator should use the same one, otherwise one of the evaluator will not be evaluated.
if funcgraph or metafuncgraph call it recursively, then anf_node should be used as tracking_id to discriminate the first occurcance and the
recursive occurance.
add anf_node to PrimitiveAbstractClosure hash() to reduce cost of GetEvaluatorFor().

ignore the tracking_id to make cse work.