Have a finer-grained approach for the resizing of the tray icon

[The4thLaw]

Description

The tray icon looks fuzzy on some OSs (including OSX)
For example, we could play with the ULTRA_QUALITY added in Scalr 4.2 (rkalla/imgscalr#61), enable or disable OP_ANTIALIAS, check if the screen is a high-DPI one or even let the OS resize (OSX seems to do that).

For MacOS:

• Tray icons should be 22xany (http://iconhandbook.co.uk/reference/chart/osx/), 44x44 on high DPI screens (https://developer.apple.com/design/human-interface-guidelines/macos/icons-and-images/image-size-and-resolution/)
• Tray icons should be black and transparent.