Optimize filtering code

[jeremykubica]

Move the current filtering code to C++ or use numba to optimize. Ideally this would take the form of a Filter class that can be overloaded by astronomers to produce their own filters. The filter code is currently called in run_search within run_search.py.

This writing new benchmarks to time the code and quantifying the changes.

[jeremykubica]

Completed in #407