Continued to develop point process via KDE.  Latest challenge is to compute the trigger KDE for all interpoint distances - slow if you truly include all of them...
Solution: implement a cutoff distance and time, using the inverted CDF to define the cutoff.
TODO: implement the inverse cdf at the kde level.
All tests passing, more needed as I continue to develop.
TODO: add tests for estimation code - eg. finding max values etc.