Release version 1.4.0

Release version 1.4.0
New commands:

• igist-post-files Post multiple files. In Dired it creates a gist
  from marked files.
• igist-print-languages-chart Print a chart with language
  occurrences.
• igist-swap-current-column Swap current column with the next one.
• igist-swap-current-column-backward Swap current column with the
  previous one.
• igist-list-remove-column Remove column.

Fixes:

• Fix column resizing for Emacs versions prior to 29.

Misc:

• In tabulated views, bind G to the revert command.
• Add Cask and Makefile for building and testing the package.