added op for pooling
fixing couple issues
added gradients
added tests
refactor c_set_tensor4d
safer c_cleanup_code_struct
added opt
testing different strides and pooling modes
fix crash
fix crash
fix test crash with floatX=float64 and FAST_COMPILE
Merge pull request #3 from nouiz/ynd-dnn_pooling

Ynd dnn pooling
added pooling opt tests
Merge branch 'dnn_pooling' of https://github.com/ynd/Theano into dnn_pooling
added opt and test for pool gradient
Add comments and code style fix for the while file
Merge pull request #2235 from RoyXue/faster_algo

Add comments and code style fix
Fix test. use float32 and enable the GPU.
pep8
Merge pull request #4 from nouiz/ynd-dnn_pooling

small test fix