Enable drag & drop sorting of ingredients in recipe/dish editor

[dboehmer]

• generic template in templates/includes/

• Sorting is secondary. Clients without JS don’t need to be supported.

• [ ] remove the current sort buttons

• [ ] create JS API for updating ingredients

• [ ] Bootstrap UI element for dragging

• [ ] JS client code for sending update requests

[dboehmer]

Bonus:

• [ ] remove column preparation, split sortable list into 2 sections (each section must exist even if no ingredient is attached to it), set preparation boolean column accordingly