Clean-up Victor Purpura distance bug fix.
Speed-up by factor of about 6.
Performance, speed-up of around 2.

measurements are quite varying ... :/
Put more code from inner for into scipy calls.
Fixing some error introduced by refactoring.
Refactoring performance improvements.
First version beating Matlab performance wise.

Needs *major* clean-up! But this commit ensures a working
version of the fast algorithm is recorded in version control.
Code clean-up.
Clean-up and refactoring.
More refactoring and speed improvements.
Improvements to the metrics profiling script.
Some comments on the optimized algorithm.
Optimization of victor_purpura_multiunit_dist.

Speed-up factor is at least around 60.

Merge branch 'feature/perf_vp_multi' into feature/stMetrics