Merge 'trunk' into 'complex_join_rels'

r20681@martha (orig r4575):  plu | 2008-07-15 04:36:20 -0400
Skip custom query sources

r20685@martha (orig r4579):  lukes | 2008-07-15 18:13:08 -0400
 r9099@luke-mbp (orig r4573):  lukes | 2008-07-14 13:11:13 +0100
 new branch
 r9100@luke-mbp (orig r4574):  lukes | 2008-07-14 15:01:50 +0100
 reordered methods of Versioned.pm and factored the initialisation stuff from upgrade to install
 r9128@luke-mbp (orig r4576):  lukes | 2008-07-15 23:07:38 +0100
 major versioning doc refactor
 r9129@luke-mbp (orig r4577):  lukes | 2008-07-15 23:11:10 +0100
 removed EXPERIMENTAL notices

r20687@martha (orig r4581):  ash | 2008-07-16 12:41:52 -0400
Update docs re txn_scope_guard