revid/pipeline.go & device/file/file.go: input looping should not be handled by processFrom routine

[Saxon Milton]

Input looping is only applicable to something like file input, i.e. it doesn’t make much sense to have processFrom handle this when processFrom is for general input processing. It only complicates the revid pipeline. Instead, the file device implementation should handle looping.

[Saxon Milton]

Resolved by PR #438