Allow permutation to return just one permutation.

fix gh-2158
Make get_scalar_constant_value() infer in Subtensor(Join of vector).

This cause some advanced subtensor to infer False for broadcast instead of True.

fix in part gh-2165
tell that tensor.nlinalg and slinalg need to be imported manually.
Remove useless user warning.
Make nonzero being printed correctly. Also get the hash and eq method correctly implemented.
[DOC] doc equivalent term to subsample
[TEST] Fix test in 32 bit python.
[CRASH] Fix typo crashing compilation introduced in 8890a7

Reported by chadawagner fix gh-2176
Respect quote in THEANO_FLAGS. This allow to don't split in some comma.

fix gh-2180
Merge pull request #2159 from nouiz/permutation

Allow permutation to return just one permutation.