Add the GPU rigid body pipeline from https://github.com/erwincoumans/experiments as a Bullet 3.x preview for Bullet 2.80

Extras/RigidBodyGpuPipeline/dynamics/basic_demo/Stubs/stringifykernelsBatching.bat

@@ -0,0 +1,8 @@
+stringify.py batchingKernels.cl batchingKernelsCL >batchingKernels.h
+
+
+
+
+@echo Warning:
+@echo You might still need to find/replace for \\n (due to macros) and replace #include statements by their content
+pause