RDB's alternative way to interpret the window size in Change

RDB's alternative way to interpret the window size in Change
Settings: it describes the size of the _unmaximised_ window.
Maximisedness is a separate property which Change Settings doesn't
affect. So if you change the font while the window is maximised, the
terminal size adjusts accordingly. The downside is that you can't
read the width and height of a maximised window out of Change
Settings. Suggestions that restore this property are welcome.

git-svn-id: svn://svn.tartarus.org/sgt/putty@1102 cda61777-01e9-0310-a592-d414129be87e