Add support for hidpi screens

IGB currently doesn't play well with screens that have high pixel densities (retina-type displays). On the mac platform there is reasonable support for scaling java applications that don't have native hidpi support, but on other platforms such as linux there's no such option. It would be great if IGB could either honor the gsettings 'scaling-factor' on linux or allow for specification of the DPI as a configuration option.

Reporter: Harm van Bakel
E-mail: harm.vanbakel@mssm.edu