Better error message on character set mismatches during conversion to unicode.

Better error message on character set mismatches during conversion to unicode.
Also applied patch from Lars Stenberg to make callable statements use the form
select * from func() when running against a 7.3 server instead of select func() to allow for set returning functions to be called.

 Modified Files:
 	jdbc/org/postgresql/errors.properties
 	jdbc/org/postgresql/core/Encoding.java
 	jdbc/org/postgresql/jdbc1/AbstractJdbc1Statement.java