Add support for most of the ESC[<low number>t sequences, which xterm

Add support for most of the ESC[<low number>t sequences, which xterm
uses to manipulate the window (minimise, maximise, front, back,
move, resize) and report things about the window (is it minimised or
maximised, how big is it, what's its title). Missing are ESC[4;X;Yt
(resize to a specified pixel size; our resize code doesn't like it)
and ESC[19;X;Yt (report size of _screen_ in _characters_, which it
isn't even obvious how to do when you've got a variable font size).

git-svn-id: http://svn.tartarus.org/sgt/putty@1414 cda61777-01e9-0310-a592-d414129be87e