Removed duplicate print code for "Fast op".

Check RST files in '/theano/doc/' to follow numpy's docstring + Fix elemwise

fix gh-4328 This was done for python3, but not python2.

Moved theano.sandbox.softsign to tensor/nnet/nnet.py. Added test. #4314

Add broadcastable dimensions in opt where needed

- Move the contribution requirements on top, so that contributors read
them even if they know how to setup GitHub
- Fix minor errors
- Remove commented code in elemwise

Pass dims as intp to PyArray_SimpleNew

Doc the new pool module

conv.cu simple comment fix

GpuJoin takes negative values for axis

Small changes.

Adding clang-omp++ as an alternative compiler to clang++ as it suppots OpenMP

fix gh-4305

fixed nosetest doc

Gpupool newbackend