Function plan 

pub fn plan(survey: Survey, mode: Mode, target: &Target) -> Result<Plan>

Decides every path of survey under mode, running the merges it needs.

A file with parts is composed: each part spliced into it, merged where it needs merging, and the whole checked. A conflict in one part holds the whole file back.

Errors

• MergeError::Unresolved, conflicts wait under Mode::Apply or Mode::Force.
• MergeError::NothingToContinue, none waits under Mode::Continue.
• MergeError::Unmerged or MergeError::Invalid, a resolution still has markers, or does not pass its file’s check.
• MergeError::Run, a merge driver does not run to completion.
• Error::Parse, a part cannot be written into its file: a key it sets lies under one the file holds as a value.