WL#2939: Add a storage engine to browse an LDAP directory as a table

I got inspired by this while listening to a PostgreSQL presentation, where they
presented "dblink-ldap" (http://pgfoundry.org/projects/dblink-ldap/) - it would
be nice to have a plugin that connects to a given LDAP server and presents the
directory content as tables to the MySQL server that can be queried as regular
tables.

[MarkM] - Perhaps taking a look at the JDBC-LDAP bridge could make a prototype
for this when we have heterogeneous federation via JDBC (which is something
EricH and I are working on for 5.1) - http://www.openldap.org/jdbcldap/