[ADQL,TAP] Fix 2 bugs notified by M.Taylor:

1/ Bad parsing of UDF's parameter type or return type. Database types whose the
name has a space (e.g. 'double precision') were not accepted. These type names
should be accepted according to TAPRegExt.
2/ An error message thrown by the DBChecker has been modified for the cases
the type of a parameter is unknown. Before the returned type was NUMERIC. Now,
it will be 'param' followed by the parameter index (e.g. 'param1').