Add NoSymbol into the keysym table, so keysym <-> string conversion works for
that, too; also eliminate special-casing of VoidSymbol.
This will require special-casing in libX11 to preserve its API.
Signed-off-by: Daniel Stone <daniel@fooishbar.org>
A test program and script have been added for checking the XkbCommon
keysym functions. This has already highlighted an error in handling of
keysyms from XF86keysym.h.