more indexes on align feature tables so range queries are still quick when no logic name is provided

Populate max_length in meta_coord table now.  Additionally, meta coord is automatically populated now and no longer needs hardcoding for each species.

Initial version of program to convert short introns into frameshifts.  Currently cannot handle all cases and needs some significant reworking.

* DBConnection now does a lazy connect (doesn't connect until first access to prepare, do, or db_handle methods).
* disconnect_if_idle can now be called by user processes and DBConnection will reconnect when needed.
* Reconnection is linked to db_handle method.  connect method will now only connect when needed.
* StatementHandle::DESTROY now calls DBConnection::disconnect_if_idle to disconnect so disconnect logic is consolidated in one place.
* New method ->connected : returns boolean as to connection state
* New Method ->disconnect_count : returns number of disconnect cycles DBConnection has gone through
* db_handle is now fork safe
* reduced number of db_handle->ping operations