update bullet so it actually works

Moved the addSourceDirectory for physics/Bullet into the Engine/Source/CMakeLists.txt file that way it can actually appear where we expect it to in the solution explorer.

Engine/lib/bullet/examples/SimpleOpenGL3/premake4.lua

@@ -17,7 +17,7 @@
 		initGlew()
 	
 		files {
-		"*.cpp",
+		"main.cpp",
 		"*.h",
 		}