add drawPoint/drawLine (both slow) and drawPoints (faster) to GLInstancingRenderer, with GLSL shaders

btgui/OpenGLWindow/Shaders/linesVS.glsl

@@ -0,0 +1,17 @@
+#version 150   
+
+uniform mat4 ModelViewMatrix;
+uniform mat4 ProjectionMatrix;
+uniform vec4 colour;
+
+in vec4 position;
+
+
+out vec4 colourV;
+
+void main (void)
+{
+    colourV = colour;
+		gl_Position = ProjectionMatrix * ModelViewMatrix * position;
+		
+}