[BRLTTY] udev rules

[Samuel Thibault]

Hello,

As reported on Ubuntu which happens to install brltty by default in its
latest release, the udev rules for braille devices with generic USB IDs
are hurting people that have hardware that use the same usb-serial chip.

Dave, could you split the udev rules file in two pieces, one with only
non-generic IDs and one with only generic IDs? That way, distributions
can install brltty by default with the udev rules for non-generic IDs,
and install the udev rules for generic IDs only when requested.

Samuel