Remove synPermActiveInactiveDec from TemporalPooler

[Subutai Ahmad]

The current TemporalPooler class has a parameter called synPermActiveInactiveDec with the associated rule:

For inactive columns, synapses connected to input bits that are on are
decreased by synPermActiveInactiveDec.

This task is to remove this rule, and all associated data structures such as _permanenceDecCache

[Subutai Ahmad]

@ywcui1990 Here's one you could take on if you wanted! We need to make sure the experiment sm_pooling_1d_test.py and sm_pooling_hello_world.py still work.

[Yuwei]

Sure. I will take a look at this.