Support for extra keys such as Ctrl, Alt, Tab and Esc on mobile devices

On mobile devices such as the iPad the user experience might be limited without the access to all keys. For example when working in a terminal the Ctrl and Tab keys are quite essential for providing a good user experience.

This patch adds Ctrl, Alt, Tab and Esc to the control bar. Since these four buttons can take up quite a lot of space, they have been put into a dropdown menu in lower resolution cases.

Touch device with high resolution:
![big](https://f.cloud.github.com/assets/4117162/855242/2dfec5bc-f51d-11e2-87da-9c66ece02341.png)
Touch device with low resolution, collapsed:
![small-closed](https://f.cloud.github.com/assets/4117162/855243/2fcf82d2-f51d-11e2-96e3-a24075bcee8f.png)
Touch device with low resolution, expanded:
![small-open](https://f.cloud.github.com/assets/4117162/855400/47d72622-f523-11e2-8386-f489cccd4de1.png)