v2.0.2 integration

- Overhaul of `dtCollisionAvoidance`: parameters moved to the behavior itself and better documentation.
- Overhaul of `dtPathFollowing`: parameters moved to the behavior itself, target setting moved to the params and better documentation.
- Clearer lifetime for agents desired velocity.
- Renaming of dtVperp2D tp dtVCross2D for better consistency.
- Renaming `dtCrowd::setAgentBehavior` to `dtCrowd::pushAgentBehavior`.
- Renaming `dtCrowd::updateAgentPosition` to `dtCrowd::pushAgentPosition`.
- Renaming `dtCrowd::applyAgent` to `dtCrowd::pushAgent`.
- Addition of the *mazy hall* DetourCrowd sample.
- Additional DetourCrowd unit tests.
- Attaching the revision tree to the new [*origin* github repository](https://github.com/memononen/recastnavigation).
- Fixing the build of DetourCrowdDemo on linux.