Controls mapping of entity obects (instances of Horde_Rdo_Base) from and to
Horde_Db_Adapters.
Public properties:
$adapter - Horde_Db_Adapter that stores this Mapper's objects.
$inflector - The Horde_Support_Inflector this mapper uses to singularize
and pluralize PHP class, database table, and database field/key names.
$table - The Horde_Db_Adapter_Base_TableDefinition object describing
the main table of this entity.