v0.1.0

Physic engine for Go game development.
This first version is still a very early release. The collision points need more stabilization (06ed770 commit seemed more stable).

This engine is built upon the XPBD solver algorithm.
The BroadPhase uses a configurable SpatialGrid.
For the NarrowPhase it combines GJK+EPA+Manifold algorithm detection for convex objects. The planes use a dedicated route collision detection.

Each step uses a given number of workers and communicate with channels, speeding up the performances.
Lot of refactorization done for memory management (overall reduced by 20 for number of allocations & heap usage), and still more required for a serious project.