xsd-fu: Add C++ templates

These are currently a duplicate of the Java templates.
Duplicate Java ome-xml implementation
cpp: Add config.h generation and initial About class with test
Remove About.java
xerces: Wrap platform
xerces: Wrap string
Fix xerces::string
xerces::string: Add const qualifiers
ome-xml: Link with Xerces
Add xerces error_reporter class
error_reporter can log to any stream
Inline header-only definitions
FIXME: Add debugging bits
Build with more checks and build xerces test
Add xerces test
Simplify xerces string
Further xerces string improvements and debugging statement removal
Indent initialisers in xerces string
Template update
Replace Boolean with bool