The last references to CastToReaders were commented out in 6faeee83
(cmds2/add: temp fix for -r. horrible hack, 2014-11-11) and then
removed completely in 032e9c29 (core/commands2: Updated 'add' command
for new file API, 2014-11-16).

The last references to CastToStrings was removed in a0bd29d5
(core/commands2: Fixed swarm command for new arguments API,
2014-11-18).