A 360° arc will have the mid point on the opposite side of the circle
from both the start and end points. This will make both slopes the
same, leading to a degeneracy in the calculation. We address this by
noting that the center will be halfway between the midpoint and the
start point.
This implements all existing symbol library object support and the ability
to save and load symbol library files between file formats for round robin
testing.
* Split up the thirdparty code into the thirdparty folder (#3637)
* Create a new kimath static library containing all the math functions
This is part of cleaning the build system for #1906.