Support for incremental backup and supporting log-only backup cursors.
Also log archiving via truncate with the backup cursor.  #1183
Incremental backup test. #1183
Change print to self.pr. #1183
Merge branch 'develop' into incremental-backup
Merge branch 'develop' into incremental-backup
Split the schema lock into a lock that prevents concurrent schema-changing operations (create, drop, rename, etc.), and a separate lock that protects the shared handle list.  The main goal in the short term is to ensure that checkpoints don't hold any locks that block cursor opens while doing I/O.
Add a lock around table operations, so that cursor opens don't see tables half created or half dropped.
Changes to allow recovery to be run between incremental backups. #1183
Lint.
Remove debugging remnant.
Fix code movement bug in opening backup file.
Merge branch 'develop' into checkpoint-concurrentcy
Implement @agorrod's review comments.
Drop the handle lock while waiting for the eviction server to clear walks.  Otherwise we can livelock.
Fix use of the table lock, which prevents tables from being opened when partially created.
Finish checkpoint locking: gather data handles in the first pass, then walk the list in subsequent passes to apply the checkpoint.
whitespace
KNF
Fix a comment.
Move a comment from the function header to the code that implements it.