Various improvements

This issue is here to provide various ideas of improvements that can be done. Of course, feel free to discuss each of the items.

• Make a new object "capabilities", listing the DPI, and various capabilities like battery level reporting and such, so that the interface adjusts accordingly.
• Add support for multiple mice. Yes, the use case is not frequent, but this may be handy. With a device selector.
• Add some sort of "profile" load/save option
• Add an option to load different profiles based on the current mouse mode. Of course, this would need the program to always be running, which brings us to the next item...
• Make a system tray icon, which will perform user-defined tasks, maybe even a button remapping functionality. I don't know if this approach to button-remapping is wayland-proof, though.
• If the tray indicator is implemented, I also reverse-engineered quite some time ago (before the mouse, actually) the protocol required to speak to the Cybork V.7 keyboard's volume indicator. We could also make the program take care of updating it.
• add a command-line interface. Would especially be handy since not everyone wants pyQt5 on their machine. It looks like @np has started something like that already. Part of this is tracked in #13

Also :

• Investigate the possibility of contributing to Libratbag
• Fix the kernel module to enable the mode button auto-release tweak on more devices
• Add battery level reporting to the kernel module. I got stuck on this : http://codepad.org/GWZPwKyX (fixed the issue -wrong read size iirc- , but didn't write the module)

This issue bundles multiple independent features, names no files or tests, and notes that CLI work is partly tracked in #13. Start by reviewing the existing Python/pyQt5 application and #13, then split the remaining ideas into separate issues. Each follow-up should name its entry points and tests and define a specific completed behavior.