Adds a setting to specify the max length of key press macros that the
device supports.
Setting MacroLength to 1 means that the device supports normal key presses,
(key + modifiers) but not multi key press macros.
0 can be used to indicate that buttons cannot be set as keys at all.
Initial support for the original Rival mouse.
Setting resolutions, report rate and LED color and
modes.
No key mappings yet, and breathing duration is fixed.
