better comments
make make_node to cast and filter_variable inputs to scan
remove old comment (TODO was already implemented)
re-order in order to first do the checks before constructing this attributes
better comments
PEP8
safe_new should return a variable not a graph
test proposed by Oliver
fix PR

the unbroadcast(shape_padleft(x)) might not be of the same type as x,
specifically when x is CudaNdarrayTyepe,  unbroadcast(shape_padleft(x))
is a TensorType.
re-add change
fix scan optimization
test the fix for the merge optimization
some comments why we do not call format
Merge pull request #1341 from pascanur/recent_scan_bugs

Recent scan bugs