Internal configuration options for TickitTerm

Increasingly the TickitTerm object (outside of the TermDriver) will need configuration options for things like maximum timing to consider for double or triple- mouseclicks, or how long to linger for ESC prefixed sequences.

We should consider whether these still want to be TermCtl options, or live somewhere else.

Additionally it might be interesting to consider whether a user-wide config file could apply, to set options for all Tickit-based applications, or whether each application will have to set them individually. In at least some cases (e.g. neovim), applications will already have a well-established configuration system; but other smaller cases may benefit from not needing to bother themselves.