Better Dark Mode for Tyler T&A

I didn't like the standard ExecuTime dark mode, so this is better. - No more lightgray-and-black striped timesheets - Calmer headers, tabs and gridlines - 13 color schemes, including Vim desert, darkblue, CRT green, and more - Custom colors for everything, with export and import to share a theme - Only works while ExecuTime's own dark mode is on Changes colors only. No data collected, nothing sent anywhere. Unofficial. Not affiliated with or endorsed by Tyler Technologies, Inc.