:arrow_up: deprecation-cop for new panel selectors
:arrow_up: atom-dark-ui for 1.0 selector compatibility
:arrow_up: deprecation-cop for atom-pane-container and atom-pane-axis deprecations
:arrow_up: atom-light-ui for 1.0 selector upgrades
:arrow_up: deprecation-cop to fix specs
Preserve 1st line's leading whitespace on paste