[meta] Rename edit module to quickedit

We renamed edit module in Drupal 8 core to quickedit module — see #1874640: Rename edit module to quickedit.
We should do the same to this project, the Drupal 7 backport, to make things more maintainable.

Steps:

1. Backport all changes to edit in Drupal 8 before commit 240392c (which corresponds to #1874640).
2. Push the existing edit module (i.e. this project) history to the new https://drupal.org/project/quickedit project.
3. Perform the renaming.
4. Backport all changes to quickedit in Drupal 8 since 240392c.
5. Move over all existing issues from this issue queue to quickedit.
6. Commit patches that are ready, like #1889798: Panelizer support (use Panels' render pipeline to re-render edited field panes in Panels).