Experimental: gtk2 pseudo-hidpi

Create a gtk2 "pseudo-hidpi" theme for HiDPI displays (which is needed A/B testing) because my laptop is not HiDPI, gtk3 remains unchanged since it has already better HiDPI support

No precompiled zip available, you need to build it (just download a Source code file)

and send feedback to "Issues" tab with hidpi tag, and PRs are welcome (also for master branch)