More performant point in polygon algorithm

[jannikmi]

The current point in polygon check algorithm is implemented in python which gets just in time compiled automatically if the package Numba is installed.

Without Numba the algorithm is relatively slow.

With Numba the first run will take considerably longer due to the JIT compilation (cf. #146).

Find an alternative solution wich is fast in all cases without any initialization overhead.

Perhaps including the algorithm as C module is a good option (cf. the package multivar_horner).

[jannikmi]

Perhaps also using other packages is a good option if they don't have a too large footprint.