- To accomodate the fact that there are now two kinds of eager

- To accomodate the fact that there are now two kinds of eager
loading available, the new names for eagerload() and
eagerload_all() are joinedload() and joinedload_all().  The
old names will remain as synonyms for the foreseeable future.

- The "lazy" flag on the relationship() function now accepts
a string argument for all kinds of loading: "select", "joined",
"subquery", "noload" and "dynamic", where the default is now
"select".  The old values of True/
False/None still retain their usual meanings and will remain
as synonyms for the foreseeable future.

- Added documentation to tutorial,mapper doc, api docs
for subqueryload, subqueryload_all, and other options.