Decouple terminal sequence construction from drivers

[alexrp]

Applications should be able to bundle a bunch of escape sequences and emit them all at once. This will require decoupling construction of escape sequences from the terminal driver.

[alexrp]

A consequence of this is that the driver will no longer be easily able to keep track of terminal state based on the methods/properties invoked by the application. To be fair, though, that state could already get out of sync if the application emitted escape sequences manually.

A better design here might be for the driver to hook into the input/output streams and have a minimal escape sequence parser to keep track of what the application is doing. This is quite a bit more involved than the current design, but it's also a lot more foolproof, and would allow us to also parse things like query responses (e.g. cursor position).