Makes more sense to split the user script into two distinct pieces of
functionality.

multi-click-to-select-code:
  * Selects all text in <code> or <pre> tags
  * Save user settings to localstorage so any customizations don't get
    overridden by automatic updates.

format-terminal-commands-on-copy:
  * Edits selected text on copy
  * Added listener to entire document rather than just the code elements
  * Easier to quickly disable just this behavior from the script manager