Add support for connector leaves in get_hash
Enable die_on_undef in Proxy::Config::Versioned->get
Fix spacing and indent, no code changes
Improve handling of undef/non exisiting file in File Connectors
Allow recursive connector/reference use, change get_meta stub

Connector::Multi now uses itself (not baseconnector) to resolv
links to connectors, which allows references inside connector
definitions (e.g. LDAP Password via KeyNanny)

The definition of get_meta method no longer includes optional return of
the value and does NOT NECESSARYLY test for exisitence of a node any longer.
If you used get_meta to test for existance, please check if the used
connectors support it.
Add generic get_size / get_keys
Add/Change get_meta methods in all connectors to match new requirements
Add get_reference call in C:P:Config::Versioned
Fix spacing in Proxy::DBI
Allow retrieval of top node in Proxy::YAML
Add tests for cascaded references / connectors