Improve speed of SP local inhibition, 70x slower than global

[breznak]

CC CUDA SP #50, SP faster LocalInho #86 , #92

From https://github.com/htm-community/nupic.cpp/pull/119#pullrequestreview-178811874 :

I'm evaluation the performance impact of ND vs 1D, where algorithmically the 1D is really simpler.

• Global Inh

  [ RUN      ] HelloSPTPTest.performance
  starting test. DIM_INPUT=10000, DIM=2048, CELLS=10
  EPOCHS = 1000
  starting:  1000 iterations.Total elapsed time = 0 seconds
  [       OK ] HelloSPTPTest.performance (1027 ms)
  [----------] 1 test from HelloSPTPTest (1027 ms total)

• Local, 1D (to be removed):

  [ RUN      ] HelloSPTPTest.performance
  starting test. DIM_INPUT=10000, DIM=2048, CELLS=10
  EPOCHS = 1000
  starting:  1000 iterations.Total elapsed time = 74 seconds
  /home/mmm/devel/HTM/htm-community/nupic.cpp/src/test/unit/algorithms/HelloSPTPTest.cpp:101: Failure
  Value of: timeTotal <= CI_avg_time
  Actual: false
  Expected: true
  HelloSPTP test slower than expected! (74,should be 45
  [  FAILED  ] HelloSPTPTest.performance (74195 ms)
  [----------] 1 test from HelloSPTPTest (74195 ms total)

• local, ND (proposed default, resp. only choice):

  [ RUN      ] HelloSPTPTest.performance
  starting test. DIM_INPUT=10000, DIM=2048, CELLS=10
  EPOCHS = 1000
  starting:  1000 iterations.Total elapsed time = 75 seconds
  /home/mmm/devel/HTM/htm-community/nupic.cpp/src/test/unit/algorithms/HelloSPTPTest.cpp:101: Failure
  Value of: timeTotal <= CI_avg_time
  Actual: false
  Expected: true
  HelloSPTP test slower than expected! (75,should be 45
  [  FAILED  ] HelloSPTPTest.performance (75335 ms)
  [----------] 1 test from HelloSPTPTest (75335 ms total)

TL;DR

• local inhibition is very slow! 70x (1s vs 74s global/local inhibition)
• this PR (1D/ND) does not change that (-> :ok: merge)
• we should work on improving speed of local inh (#50 )
• there are no unit tests for local inhibition!

[breznak]

Thanks to PR #769 local inhibition (only for wrapAround=true) is now 2x faster!

local inhibition is very slow! 70x (1s vs 74s global/local inhibition)

which equals to improvement and it's now only 10x slower than global inh!