Replace VectorEncoder usage

[scottpurdy]

@BoltzmannBrain discovered some of the research code is broken due to obsolete VectorEncoder usage. You can replicate the bug with python experiments/sm_test_with_pooling.py from the sensorimotor directory.

It should be fairly simple to swap out the VectorEncoder for another encoder for the motor command.

[BoltzmannBrain]

With the removal of VectorEncoder, is there now an intended replacement encoder in nupic/encoders?

[scottpurdy]

Can you use a category encoder for the motor commands? There is also a pass through encoder if none of the existing encoders provide what you want.

[BoltzmannBrain]

A category encoder may not be a good solution b/c there's no category list associated with the motor commands; there's a pool of all the sensory elements, but none for the motor commands. Where can I find the removed VectorEncoder code?

[breznak]

there's a PR on 'removing unused encoders' under Nupic, where I mentioned I will probably need VectorEnc too. You can find the removing commits and revert and bring it back either to nupic or nupic.research.

[BoltzmannBrain]

Thank you @breznak, here's the PR. I'll take a look today.

[scottpurdy]

I think it should be very easy to add multiple identical encoders without the need for a VectorEncoder.