Fix a compiler warning in test/format.
Update extension API names from txn_XX to transaction_XX.
Cut release 1.6.2
Bump develop release version.
Force the release date to be updated when cutting a release.
refs #580
Generalize the cursor "overwrite" configuration to apply to insert, update and remove.  Default to true, so LSM is no longer a special case.
refs #512
whitespace
typo
If overwrite is the default, do the cheap test first, testing to see if
the cursor referenced item is valid is a more expensive test.

Fix a comment.
cursor/cur_std.c: In function ‘__cursor_runtime_config’:
cursor/cur_std.c:402: warning: unused variable ‘ret’
lsm/lsm_cursor.c: In function ‘__wt_clsm_open’:
lsm/lsm_cursor.c:1065: warning: unused variable ‘cval’
Check all of the combinations of record exist/not-exist and overwrite
on/off for the insert, remove and update methods.   Add an LSM test,
it has a different code path.
Add an upgrading section on the new overwrite configuration semantics.
Minor edit to the upgrade wording for the overwrite API change.
refs #512
typo
Merge pull request #512 from wiredtiger/overwrite

Make "overwrite" default true and apply consistently to insert, update and remove operations.
Update Doxygen script file to be compatible with Doxygen 1.8.4
Building on a 9.1 FreeBSD release.
Merge branch 'develop' into logging