Support v. 1.3 metatype namespace

Support the R6 v 1.3 metatype schema version. The changes currently are:

• new namespace
• AD are now optional (not currently validated on earlier versions)
• AD type "Char" spelling corrected to "Character".

In line with the Eclipse metatype service I'm going to allow both "Character" and 'Char" in any namespace. If anyone objects I'm happy to change this to validate which namespace each is valid under.