Add history support for all griddly settings

History support for modern browsers that support history API. Any changes done to a grid will reload on navigation back to the grid from another page. No additional history entries are created, and no persistent history is created.

Selection isn't currently saved, but that functionality may be added in a subsequent revision.

No breaking changes.

If you are not including griddly.css, add the following to your custom griddly css to hide the Griddly on navigation until it can be reset and reloaded:

.griddly-init-flag[value=loaded] + .griddly.griddly-init {
  display: none;
}