Made robot lights shiny

The red light in the centre is now actually bright. Makes robots easier to spot at night i guess, but I did it mostly because I thought it looked cool.

Also cleaned up the class a bit, got rid of useless parameters and sorted things out a bit.
And got rid of the try/catch for the texture binding. The NPE was being thrown when the game was loaded and the entity rendered before it got the chance to create it's ResourceLocation (which is done after it ticks at least once if I remember correctly), so the whole try/catch could simply be replaced by a null check.

Night:
![night](http://i.imgur.com/VMR8gWZ.png)

Day:
![day](http://i.imgur.com/5pepqKz.png)
Why not GL11.glDisable(GL11.GL_LIGHTING)? Just asking.