Start on RecordStore API tests.
Add tests for storageSize().
Add tests for dataFor().
Add tests for deleteRecord().
Add tests for insertRecord().
Move StringDocWriter to its own header file.
Start on tests for updateRecord().
Add test for updateRecord() with non-NULL move notifier.

The record need not be moved; however, if the DiskLoc returned in the
status is different than the old position of the record, then the
move notifier must have been called.
Start on tests for updateWithDamages().
Add updateWithDamages() tests for overlapping `DamageEvent`s.