Remove the remaining bits of deprecated GL usage

The drawing is now completely shader based, which makes away
with all usage of the depracted matrix stack. This also allows
us to do things like simple translations and texture coordinate
translation directly instead of doing everything indirectly
through matrices.

Fixed vertex attributes ('vertexPointer()' etc) are also
replaced with user defined attribute arrays.

shader/simple.vert

@@ -0,0 +1,18 @@
+
+uniform mat4 projMat;
+
+uniform vec2 texSizeInv;
+uniform float texOffsetX;
+uniform vec2 translation;
+
+attribute vec2 position;
+attribute vec2 texCoord;
+
+varying vec2 v_texCoord;
+
+void main()
+{
+	gl_Position = projMat * vec4(position + translation, 0, 1);
+
+	v_texCoord = vec2(texCoord.x + texOffsetX, texCoord.y) * texSizeInv;
+}