fix intro stretching
resizing behaviour infrastructure

includes stuff for options screen adjustments and whatnot
resizing behaviour infrastructure

dynamically resize the battlescape and geoscape based on scale options.
maintains pixel size at all times.
fix for bug 553
Merge branch 'master' of https://github.com/SupSuper/OpenXcom into statStrings
Merge branch 'master' of https://github.com/SupSuper/OpenXcom into statStrings