Topological order

The idea is to sort addins in a topological order. Each addin can define one of five things for _order_:
* `>X` - I must be immediately after the addin with id X

* `>>X` - I must be somewhere after the addin with id X (but not necessarily immediately) 

* `<X`- I must be immediately before the addin with id X

* `<<X` - I must be somewhere before the addin with id X (but not necessarily immediately) 

* `Number` - A numerical order which is used if none of the above is applicable


can you provide details into the nature of the conflict?
which addins are involved, what the circle is, etc?