Added doc on sliding windows related operaitons
Fixed spelling
Added more info about inputs and restrictions
Fixed neigbours doc according to remarks
Merge github.com:Theano/Theano into doc_fix
Moved neighbours into tensor.nnet
Fixed typos, merged documentation, added references
Added information about gradient computation
Merged documentation with docstrings
Fixed ordering of documentation
Fixed punctuation, fixed #2166
Merge pull request #2197 from dmitriy-serdyuk/doc_fix

Documentation for sliding windows