fixed shutdown of shared XML backend when file already locked

Change-Id: I62d6d164f86d4e70b439b2ceb4a1e1bfac7b6b1f
implemented remaining FdoUI methods in Paratext plugin

made strings localizable

Change-Id: I3af1e796c879c4a60dd29fdb19a0ffd561f9b5d9
restricted changing custom fields when using shared XML backend

Change-Id: I6566de4fb9e12024724f7534b8b764fc6331a941