Various metadata issues

1. The default for a proc/function should be virtual and the keyword foreign should be used to indicate a source function.
2. The parser should validate a source procedure has no procedure body defined
3. The parser should validate a function has no function body defined.
4. FunctionMethod.getFullName should not use category qualification.
5. A DDL defined function should be schema scoped when referenced in the getSupportedFunctions list
6. MetadataFactory should not extend Schema to avoid the merge operation and to not serialize MetadataFactory information with the objects created.
7. Schema should not have visibility metadata - that is held on the ModelMetaData.