CSI Excapes not handled by termion cause panic

[joelakuhn]

Some valid escape sequences like shift+right (1;2C) are not properly parsed by termion and therefore return an Err result. This causes a panic in the input loop of App.run, which unwraps the event variable yielded by the input iterator.

[PaulJuliusMartinez]

Ah, I think I expected errors like this to be returned using the Event::Unsupported variant. Evidently not the case.

I've removed the unwrap and provided actual error handling in b681708. (I should clarify the error prefix from Error: to something like Input Error: or Error getting user input: though... An inadvertent key press may result in a confusing error message. I'll think about it.)

Thanks for the report.