Refactored GJK, EPA and MPR as a template class, reducing/removing the dependencies

to the rest of the Bullet code base. This code will replace the original GJK/EPA
in a future commit.

Added btMprPenetration, an implementation of Minkowski Portal Refinement
by Daniel Fiser. Original MPR idea is by Gary Snethen, and the first
implementation is here: https://github.com/erwincoumans/xenocollide
It is an alternative to EPA, although computing the local penetration depth.
EPA computes the global penetration depth. In many cases, MPR is sufficient
and performs better than EPA.

build3/premake4.lua

@@ -116,6 +116,7 @@
 	if not _OPTIONS["without-gtest"] then
 		include "../test/gtest-1.7.0"
 --		include "../test/hello_gtest"
+		include "../test/collision"
 		include "../test/TestBullet3OpenCL"
 	end