libtmt revival

[MurphyMc]

I get the sense that libtmt does not top your list of priorities at this time, but I've recently done a chunk of work on it and wanted to make sure you were at least aware whether you decide you want any of the changes or not. If for no other reason than so you know that your work on libtmt continues to be appreciated!

(I actually wouldn't recommend just pulling this at any rate, since it includes some potentially breaking changes, e.g., it's more aimed at the "linux" terminfo entry than "ansi" now. "ansi" was no longer working right for me... I suspect changes to the terminfo database broke things, but it also could have been something in tmux.)