Improvements to srifMake

[Jonathan Tamsut]

srifMake is a function that takes as input data from trajvarsv2 and then records if a given trajectory endpoint is in a polygon. This is done using the ray casting algorithm and a helper function that checks whether a given ray intersects a line or not. This helper function is called check_intersect and takes as input a list of decimal degrees. Each of these specifies the lat and long of a point on a srif polygon.