Make great circle metric more robust (#15)

This change makes the calculation of the great circle distance more robust against rounding issues.

Rhumb line support for interpolation

This update adds optional support for rhumb lines. If enabled, segments of the polyline are interpolated using rhumb lines instead of great-circles. For both settings, the great-circle distance is used internally for finding the smallest distance between the interpolated segment and geodetic-coordinate points.

Fix issue with degenerated trajectory

A degenerated trajectory where all points are equal has caused problems during the normalization of the normal vector. This is now fixed and this case is covered with a new unit test.

Improved implementation of RDP algorithm

This update replaces the recursion-based implementation of the RDP algorithm with a stack.

Release version 2.0.0

This release brings a significant performance enhancement to our geodetic-coordinate polyline simplification library. We have replaced the computationally expensive WGS84 ellipsoid distance calculations with a more efficient and accurate spherical approximation of the Earth. This change significantly accelerates the filtering process while maintaining the high-quality simplification results you expect from GeoRDPy.