Adds a Dialog js class that will replace the jQuery UI Dialog.
Use Alchemy.Dialog instead of jQueryUI.Dialog for all overlay windows.

- Renames `Alchemy.openWindow` -> `Alchemy.openDialog`
- Renames `Alchemy.closeCurrentWindow` -> `Alchemy.closeCurrentDialog`
- Renames `link_to_overlay_window` helper -> `link_to_dialog`
- Renames the `toolbar_button` `overlay_options` -> `dialog_options`
Adds `Alchemy.ConfirmDialog` class and use this instead of jQueryUI one for confirm windows.

- Renames `Alchemy.openConfirmWindow ` -> `Alchemy.openConfirmDialog `
- Renames `link_to_confirmation_window ` helper -> `link_to_confirm_dialog `
Updates jquery-ui-rails gem and removes jQueryUI.Dailog \o/
Use Alchemy.Dialog for Alchemy.TrashWindow
Load the ElementsWindow spinner on next animation frame.
Fixes sizes and padding of several dialogs.
Render proper message after clearing element clipboard.
Use Alchemy.Dialog for link overlay.
Updates jquery ui nestedSortable plugin.