Changes from grey.colorado.quarter r2 in support of Qt5.
grey.colorado.quarter r3: Linux compile fix.
grey.colorado.quarter r8: Qualify the Qt5 QtGuiApplication fixes for highdpi.
grey.colorado.quarter r33: Robust updating of devicePixelRatio -- need to check in every render as that is the best place to get every change -- works perfectly now.
Original pull request by Bastiaan Veelo (Bitbucket: veelo, GitHub: veelo).
Reintegrates the work on high DPI (retina display) from https://grey.colorado.edu/emergent/index.php/Coin3d, courtesy Randall O'Reilly.
Changes from grey.colorado.quarter r2 in support of Qt5.
grey.colorado.quarter r3: Linux compile fix.
grey.colorado.quarter r8: Qualify the Qt5 QtGuiApplication fixes for highdpi.
grey.colorado.quarter r33: Robust updating of devicePixelRatio -- need to check in every render as that is the best place to get every change -- works perfectly now.