Processor: add some failsafe checks for old 6.2.1 processor commands

Layers required PD to explicitly state targets for various processor
commands, e.g. "Rotate image" vs "rotate layer".  Users coming from
6.2.1 may have macros that reference the old target-less commands (e.g.
"Rotate").  To try and preserve their experience, PD will now catch
those old commands, and forward them to the full-image variants of those
functions.