Provide a means to set order to nav and section items

[ChrisCorrigan]

For the main nav there is currently no way to set their order/priority. If they were classed with their name this could be one method to accomplish it.

For sub sections we currently have to prefix their name with an index (number or letter) to force the order we want. This gets messy when we need to move sections around or add new ones into the order, having to update the naming for all the others.