move build to build3 to avoid naming conflict with Bullet 2.x

fix build error in BasicGpuDemo
Thanks to joen66 for the report here:
https://github.com/erwincoumans/bullet3/issues/5

build3/findOpenGLGlewGlut.lua

@@ -0,0 +1,51 @@
+
+	function initOpenGL()
+		configuration {}
+		configuration {"Windows"}
+			links {"opengl32","glu32"}
+		configuration {"MacOSX"}
+ 			links { "OpenGL.framework"} 
+		configuration {"not Windows", "not MacOSX"}
+			links {"GL"}
+		configuration{}
+	end
+
+	function initGlut()
+		configuration {}
+		if os.is("Windows") then
+			configuration {"Windows"}
+			includedirs {
+				projectRootDir .. "btgui/OpenGLWindow/Glut"
+			}
+			libdirs { projectRootDir .. "btgui/OpenGLWindow/Glut"}
+			configuration {"Windows", "x32"}
+				links {"glut32"}
+			configuration {"Windows", "x64"}
+				links {"glut64"}
+		end
+		
+		configuration {"MacOSX"}
+ 			links { "Glut.framework" } 
+		configuration {"Linux"}
+			links {"glut","GLU"}
+		configuration{}
+	end
+
+	function initGlew()
+		configuration {}
+		if os.is("Windows") then
+			configuration {"Windows"}
+			defines { "GLEW_STATIC"}
+			includedirs {
+					projectRootDir .. "btgui/OpenGLWindow/GlewWindows"
+			}
+			files { projectRootDir .. "btgui/OpenGLWindow/GlewWindows/glew.c"}
+		end
+		if os.is("Linux") then
+			links{"GLEW"}
+		end
+		configuration{}
+	end
+
+
+