Improve the calculate_ratios method.

	modified:   Layouts.pm

Pull in improvements from "layout" branch for calculating ratios.
Now ratios can be actual ratios, not just percentages.
add check_args method
add check_args method
clarification
Checking maximization behaviour.

If UseMaximize is false, and a window is currently maximized,
then don't change its size when one is arranging windows.

modified:   lib/FvwmPiazza/GroupWindow.pm