One-to-many support.

There are a few changes here.

 * Bidirectional relationships are handled internally, so the user doesn't have to mark one an inverse anymore or pay attention to that (this was causing lots of problems with one-to-many.)
   This is done by temporarily caching just the prior Entities that could induce the circular reference.
   In order to support this, the Primary Key is the first field to be filled when an Entity is loaded.

 * One-to-many support.  This adds a List TypeMapping, however the only supported list is currently an Entity list.

* Simple order by in DESC.

* Close leaked cursor.

There are a few white-space removals, I apologize for that.  My editor auto trims.