Allow "wt salvage" of any URI.
Copy log files before data files in hot backups.  This addresses a problem where recovery rolls the metadata forward past the most recent checkpoint in a data file, so that it can no longer be opened.

refs #976
Make sure changes performed by the checkpoint transaction are logged.

refs #972, #979
Change to always copying log files during hot backup, regardless of whether a target was specified.  Recovery can cope with missing files.  Fixes a warning:

src/cursor/cur_backup.c:205:5: error: 'target_list' may be used uninitialized in this function
Merge branch 'develop' into optional-verbose