don't save maximized window position to config

it seems a 'configure-event' is sent before each 'window-state-event'
when the window is maximized, so the code is checking the stale value of
cfg.maximized, and saves the new position when it shouldn't.

it may be this only happens on win32, but the new code should work
correctly everywhere.
restored window position slightly off every time

default GTK 'gravity' setting seems slightly buggy on win32, and
'static' gravity avoids the problem. this should also work well
(better?) on other platforms, but it's untested, so..
Merge pull request #106 from zombie/window-positioning

fix two small window positioning bugs