packer: Add Machine func to Ui
packer: Rename ReaderWriterUi to BasicUi
packer: renamed PrefixedUi to TargettedUi
packer: BasicUi doesn't do machine-readable, just log
packer: Add MachineReadableUi
packer: TargettedUi properly targets machine-readable data
parse --machine-readable and set it
packer: output a newline after each MR line
packer: replace new lines with literal \n
packer: replace \r with literal on Ui for MR
packer: document machine-readable
packer: -machine-readable not double hyphen
website: document machine-readable
packer: version machine-readable output
Merge branch 'machine-readable'

This adds the -machine-readable flag to Packer which turns all output
into machine-readable format. This is documented within the website
source.
Update CHANGELOG