Denote if layer compiled in the GUI

[isaacgerg]

It would be nice if there was an icon indicating that the layer in the visualization has been compiled or not. Furthermore, if the quiver isnt doing anything, it should be compiling layers in the background.

Not sure if this is an issue for tf, but in theano, it takes quite a bit of time to compile to sublayers.

Update 1
Tested with tf and th. It appears this is a th issue as tf compiles very quickly, essentially real-time. I am using th 0.8.2, windows 7.