#11 Fix for multiple line pasting into the REPL

A potential solution for https://github.com/lukebuehler/CShell/issues/11

This change subscribes the ```textEditor``` to an event, ```TextEditorOnPreviewKeyDown```, that recognizes a paste action and sanitizes the input in the clipboard.

The data in the clipboard remains exactly how the user copied it.

This:
![replcopytextsource](https://cloud.githubusercontent.com/assets/1616060/3127432/7166606e-e7be-11e3-8966-424121decfa6.PNG)

Would paste as:
![replpasteexample](https://cloud.githubusercontent.com/assets/1616060/3127441/c14422ec-e7be-11e3-8e03-3967f724fb73.PNG)