A catalog written before the lens data was read at import (RW2/RWL from
v0.4.0) has none stored, and the lens correction stays off. Reload now
stores the fresh probe's lens data (new journaled, undoable
Op::SetEmbeddedLens; catalog format 4) and, for photos still at import
settings, switches the correction on as import does. Edited photos and
photos with a default-preset look keep their settings.