* compute_test_value=True enables on-the-fly execution of perform method
* the user provides default test values through the tag scratchpad, i.e.
T.dmatrix().tag.test_value = numpy.random.rand(4,6)

Also remove the test that used them.

We use the ShapeFeature and SpecifyShape, now,
tag.shape is being deprecated.

Thanks Fred for the review.

This avoids adding extra keys into the cache whenever these options change.

- Avoid actually compiling a module when it has same hash as an existing one
- Simplified the get/release lock stuff in some functions
- Added ability to log messages directly when calling _rmtree

Fix a crash following the new meaning of CudaNdarray.base to always point to the variable that contain the data.