Merge 'trunk' into 'replication_dedux'

Merge 'trunk' into 'replication_dedux'

r13798@dev (orig r4486):  lukes | 2008-06-10 15:08:17 -0500
 r8139@luke-mbp (orig r4482):  lukes | 2008-06-10 17:25:34 +0100
 new branch for making the FK index optional
 r8140@luke-mbp (orig r4483):  lukes | 2008-06-10 20:09:24 +0100
 added some perldoc
 r8141@luke-mbp (orig r4484):  lukes | 2008-06-10 20:40:42 +0100
 allow add_fk_index param to be specified in rel def
 r8142@luke-mbp (orig r4485):  lukes | 2008-06-10 21:07:56 +0100
 fixed failing test

r13800@dev (orig r4488):  castaway | 2008-06-11 07:25:15 -0500
Point at "prefetch" in the get/set cache docs

r13801@dev (orig r4489):  castaway | 2008-06-11 07:54:58 -0500
Add docs to update mentioning scalar refs and discard_changes