v0.1.9

• Now rlang is in Depends.
• Output for gating() now includes a diagnostic message saved as a character string for reference in a slot called note.
• A diagnostic message can be viewed running rlang::last_error()$out$note after the unsuccessful run of gating().
• Removed redundant @importFrom fields image.plot in 'package.R'
• Added Zenodo DOI