Added built-in iterable method for fixed bandwidth KDE to remove Python
for-loop.  Not providing better speed right now, but probably due to the
implementation in the pyx file.
Amended initial estimation function in point process algorithm to allow greater flexibility.
Amended setup-c code to enable one-shot compilation.  TODO: to distribute this, need to simplify and bundle with the cpp file rather than with pyx.
Added to pyx code to expose built-in iteration method of KDE class, but this is NOT faster.  Something must be going wrong when calling it - probably to do with casting np vector to C++ vector.
Added matplotlib config file, but need to specify the backend because it has broken interactive plots atm.