Improve system tray

[nicholasyoder]

Motivation

• Icons in the system tray often have randomly colored pixels around the edges
• Is still using Xlib instead of xcb for a number of things
• Highlight on hover doesn't work correctly - when the cursor is actually over the icon itself the highlight disappears

Solution

Figure it out. Research SNI, and maybe use some of the code from the SNI plugin that is currently unused.
Sometimes when making it repaint by moving mouse on and off the bad pixels around the edge blink on and off. Maybe grab multiple versions of the icon and merge them, removing anything that isn't the same?