Fix two bugs reported by Nicolas

Conflicts:
	theano/scan_module/scan_op.py

New optimizations scan

Fix tests when OpenMP is not available

Fix for test of exp2 inplace on an int.

Minor fixes

Add sort method and tensor.argsort function

The problem is that node.op was still pointing to "self", not the
newly-created "op", so make_thunk still failed the first time.

Conflicts:
	theano/scan_module/tests/test_scan.py