If a key is not listed in keymap.cfg but SDL provides a good enough name
for the corresponding scancode, a keymap entry is generated automatically.
If a key can't be found when adding a bind, it is checked, if SDL can
resolve the key name. The resolved keybind is then used to recreate the
keymap entry - and the bind can succeed.
Some SDL names for scancodes may not be usable as keymap names: if the
name contains (, ), $ or ", it will be rejected. Also, SDL does not
provide names for all scancodes. Scancode names provided by SDL can be
platform-dependant, therefore recreating the bind may fail on a different
platform.
However, the feature should work fine with most nonstandard keys - and the
information written to clientlog can be used to amend keymap.cfg
