* add dropout

* add reshape

* add slice

* refien slice unittest

* refine slice unittest

* add cpu bf16 kernel

* migration of functors in paddle/fluid/operators/eigen and paddle/fluid/platform/eigen_ext.h
* update path of data types like float16.h in includes in extensions.h

* modify kron OP to complex template types

* modify reshape, slice, trace, transpose OPs to complex template types

* modify to complex template types in eigen slice files

* change to complex template types for pad.cc and pac.cu

* format code style

* optimize OP's compilation time, test=develop

* add more op and run ci test, test=develop

* CUDA Kernel register in cc file, test=develop

* fix macros, test=develop

* fix undefined symbol error, test=develop

* fix compilation error and undefined symbol, test=develop

* fix compilation error on Windows, test=develop

* fix compilation error on Windows, test=develop