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