r3338: More work on the winreg RPC server. Opening hives is now supported, most other...

r3338: More work on the winreg RPC server. Opening hives is now supported, most other calls
return WERR_NOT_SUPPORTED for now.

Hive backends can be set like this:

registry:HKEY_LOCAL_MACHINE = ldb:tdb://registry.tdb
registry:HKEY_CURRENT_USER = gconf
registry:HKEY_USERS = dir:/tmp/registry
registry:HKEY_CLASSES_ROOT = nt4:/path/to/NTUSER.DAT
registry:HKEY_PERFORMANCE_DATA = w95:/path/to/USER.DAT