Added a transparent chat window

Added a transparent chat window to the top left corner. The window can be moved by click on it and dragging it.

Relevant keys are: 

Y - Chat
F9 - Toggle Chat

In the KMP options panel you will find two buttons to set the binds for chatting and toggling the chat. There's also a "reset chat" button that restores the chat window to position (0, 0)

Right now when Y is clicked, the input appears along with a send button, however, pressing enter will also submit the text. 

Feedback needed on: 

* Leave the button for windows users too? Only Linux users absolutely need it. For windows its optional.
* Is Y a good key for toggling the chat? I was also considering the Tilde/BackTick.. Since Y could be too close to T?

Images:

![chatbutton](https://f.cloud.github.com/assets/226540/1489020/db6d57fa-4760-11e3-966b-cb0b02bb4f17.PNG)
![chatnobutton](https://f.cloud.github.com/assets/226540/1489021/db6e68fc-4760-11e3-89e8-5be36eaf6236.PNG)