High Level Shader Language (HLSL) & Lights

Made some changes to the lights:

• Adding a light in the scene now creates a graphical sphere to represent it
• On mouse over the light it changes from yellow to a highlighted red
• Clicking the light displays a graphical wireframe sphere of the lights radius
• You can move the light around the scene using the mouse
• The properties for the light now includes the Colour and Enabled properties

Also started work on adding High Level Shader Language (HLSL) support. Just managed to get per-pixel specular highlights working (without textures yet). Probably going to mess around with effects for the next week or so.