canvas_menu_manager 1.0.0-beta3

Bug fixes

- Menu link of a newly created page was unpublished after saving or
publishing the page, even though "Add to menu" was checked.

Two causes:
1. A form submit handler synced the hidden form values on every Canvas
page data update. For a new page these values still said "disabled",
so the freshly created menu link was unpublished again. The handler
(and the now empty canvas_menu_manager.module) is removed. The panel
already saves through the link-sync and tree endpoints.
2. After publishing, Canvas resets its page data store. The panel took
this for an undo and restored the state from page load (menu
disabled). The last saved state is now the baseline.

Notes

- No API, config or database changes. No update.php needed.
- Clear caches after updating. Hard-reload the Canvas editor to load the
new JavaScript.
- Menu links that were already unpublished by this bug must be enabled
again manually (check "Add to menu" on the page).