* 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.
Changes SHAPE_CONVEX to SHAPE_SIMPLE to better reflect the limitations.
Changes SHAPE_LINE_CHAIN::PointInside calculation to allow points
strictly inside a line chain
Fixes: lp:1768862
* https://bugs.launchpad.net/kicad/+bug/1768862
add overloads for NODE::Add( ... ) taking pointers to specific item types (retain old private add-Functions, they will come in handy later)
LINE overloads now take by reference, to document their special treatment.
updated code throughout affected by these changes