Only count clicks if the mouse hasn't moved

This fixes issues in windows, such as double-clicking
to fullscreen also advancing text, and clicking to gain
focus doing the same. It's also "standard" with how other
programs work.
Fix "maximize clicks" being counted in windows

In windows, double clicking the titlebar sent a click event.
This commit makes ponscripter ignore these.

It also, more strictly, ensures that a click event only occurs
if a mouseup follows a mousedown in the same position.
Merge pull request #54 from sekaiproject/MouseClicks

Handle mouse click events better, work around a couple windows click bugs.