adds an LDAP gateway to the server. It supports TLS if configured for the webserver, using the same parameters. It is a read only interface, only supporting bind via the configured posix password.
Fixes#101, concurrent caching of IDL and Entries. This yields a 10% improvement for test case execution, and 35% for tests run under --release mode. A lot of code around the code base was needed to be touched due to the extra need for mut in some operations and some lifetimes, but the majority of the work was in idl_arc_sqlite.rs, which has the cache layer. There are many performance gains yet to see, but most of those will come through improvement of the concread ARC and it's related BTree implementation.
Implements #127 and #125. This adds domain_info support, and spn types and generation. It also correctly handles domain renaming, and has tooling to support this. It "should" work on an upgrade, due to the correct bump of index version, but I plan to test this from a backup of my production instance soon.
