More clean up and variable renaming.
Minor comments clean up.
Rename and reorder nlmeans parameters.
Add origin patch weight tuning parameter.
Rename some variables and relocate some parameter validation.
Make sure smallest weight in exponential table is > 0.

Solves a problem with occasional black pixels peppering the edges of the output.
Remove unnecessary (at this stage) frame buffer.
Plug a memory leak.
Revert smallest weight in exponential table change.

Did not solve the problem for which it was intended.
Implement temporal filtering for nlmeans.
Improve nlmeans temporal filtering and clean up for release.