Add `UnknownCSI` event type
Created by: gyscos
When a CSI sequence is not parsed by termion, return a special UnknownCSI event including the byte sequence, allowing applications using termion to do their own parsing.
Created by: gyscos
When a CSI sequence is not parsed by termion, return a special UnknownCSI event including the byte sequence, allowing applications using termion to do their own parsing.