Fix mostly written by Fred.
Tested in Python 2.7 and Python 2.5.

Updated documentation for installation on MacOS

adding callback argument to VM_Linker

Refactored graph.inputs + new method graph.ancestors.

Fix tests with complex numbers

Fix for nvcc compilation crash in MacOS X

We should not try to access C array before index 0!

This is a fix for the situation reported here:
    https://groups.google.com/group/theano-users/browse_thread/thread/374ec2dadd3ac369/024e2be792f98d86

On a 32-bit machine, numpy.take may refuse to use int64 arrays for indices.
(incl. typo fix by @dwf)

Doc comment

Blas opt fix

Traceback comments

Removed keep_wrt_type parameter of tensor.grad

The reason I had added this parameter in 0b8b021c was to let the user get rid of
annoying warnings. However, I probably shouldn't have given the option to keep
the old behavior with no warning, since this behavior was unintuitive and
potentially dangerous. Since the warning was removed by 965afb68, it seems
pointless to keep this extra parameter that adds extra complexity to the
tensor.grad interface with no benefit.

Import fix

- Reordered imports in a more logical way
- Uniformized notations to use tensor.* everywhere instead of T.*, basic.*,
  theano.tensor.* and theano.tensor.basic.*