Fix test

Add unsigned integers to sparse.

NEWS: Add astype to SparseVariable (Nicolas B.)

Mixed

Sparse elemwise

Docstring

NEWS: Make a good sparse tutorial (NB)

Try to see which tests trigger build failure
No NEST.txt, fix to new op since the last release.

make Prepend_scalar_to_each_row and Prepend_scalar_constant_to_each_row op with with other dtype then floatX.

Fix failure under 32-bit python

Add missing import

Monoid

NEWS:
Added sparse Binomial, csr_fbinomial, csc_fbinomial, csr_dbinomial, csc_dbinomial,
Moved out of sparse sandbox:
SpSum, sp_sum, ColScaleCSC, RowScaleCSC, col_scale, row_scale, Diag, diag, SquareDiagonal, square_diagonal, EnsureSortedIndices, ensure_sorted_indices, clean)
added sparse.sqrt,sqr,log1p,floor,ceil,sgn,round_half_to_even,arctanh,tanh,arcsinh,sinh,arctan,arcsin,tan,sin}