lua-utils: funcbridge fixes for custom murphy Lua object types.

lua-utils: funcbridge fixes for custom murphy Lua object types.

Fix signature parsing to properly extract type information for
custom object types (ie. without an extra leading '('). It's
really strange this had not been caught earlier, as I recall
this having been used already elsewhere. Hmm...

For symmetricity, allow funcbridge invocations to use 'O' as
the signature for (custom murphy) Lua objects.
to see how this was not caught earlier... I recall the same