[GeoLib] Restructured and fix bug in isPointInTriangle code.

Impl. a new algorithm for checking if a point is within a triangle and removed old sources for this task.
[GeoLib::Triangle] Using existing code for containsPoint().
[GeoLib] Tests for isPointInTriangle().
[GeoLib] getOrientedTriArea() -> calcTriangleArea().

Renamed and slightly modified algorithm to make it more readable.
[MeshLib/NumLib] MathLib::calcTriangleArea() -> GeoLib::calcTriangleArea().
[MathLib] Remove twice implemented functionality.
Merge pull request #417 from TomFischer/GeoLibTriangle

GeoLib Triangle bug fix