core: added support for raw and catch-all console command handlers.

core: added support for raw and catch-all console command handlers.

Raw command handlers get their input in the original raw/untokenized
format only with the command group and command name separated from
the actual arguments.

Catch-all command handlers are fallback command handlers that get
invoked for all group commands without a matchink handler. IOW, if
a group has a catch-all handler the core console will never give an
error about unrecognized commands but rather invoke the catch-all
handler for these.