Various small rendering tweaks to robots.

Robots are awesome and everyone knows that, but I felt they looked a bit strange...
Here's what I've changed:
-They use lighting when rendering (both as entities and items).
-They look bigger when on inventory slots. Makes it easier to identify which robot is which.
-They used to cover half of the screen when held in hand. Now they render a bit lower.
-When dropped on the floor they bob and look a bit smaller (as consistency since they aren't as big as a normal sized block).
-Deleted a huge method that didn't do anything.

-Also, I think that if the red light in the centre of each robot's face glowed in the dark it would look rather fancy. I'll make a PR for it if it's a wanted :3

Dropped
=============
Before
![entity-before](http://i.imgur.com/Sjzdcra.png)
After
![entity-after](http://i.imgur.com/hsN2deM.png)

First Person
=============
Before
![firstperson-before](http://i.imgur.com/YEmVdbe.png)
After
![firstperson-after](http://i.imgur.com/IiEeKO1.png)

Inventory
=============
Before
![inventory-before](http://i.imgur.com/v3jyyUu.png)
After
![inventory-after](http://i.imgur.com/LbRYJnf.png)

Docked
=============
Before
![docked-before](http://i.imgur.com/TEi6QZz.png)
After
![docked-after](http://i.imgur.com/yhAn8fX.png)