Fix segments contains

[Kubuzer]

This Pull Request implements the missing non-convex (concave) shape support in h2d.col.Segments.containsPoint and introduces a headless unit testing suite.

Changes:

• h2d.col.Segments: Replaced the placeholder throw "TODO" exception in containsPoint (when isConvex = false) with a ray-casting (winding number) algorithm to support concave polygons.
• Testing Suite: Created a lightweight testing framework under test/ running on the Haxe compiler interpreter (--interp) to ensure headless tests can run on any platform.
  • Added math tests for hxd.Math (clamp, nextPOT, isPOT, lerp, etc.).
  • Added collision tests for h2d.col.Segments verifying both convex and concave polygon containment.
  • Added regression test for h3d.impl.ShaderCache ensuring shaders are cached in memory when allowSave = false.

[yuxiaomao]

I think we'll not accept unit test files for the moment, please remove it from this PR