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


you have 2 conditionals. the first one throws an error, so you saved on writing the "else" before the second.
consider that you might one day change the behavior inside the first conditional to not throw an error.
will you remember to add the else then? probably not.
i suggest putting the "else" in anyway. it doesn't cost you anything, and it's a good habbit IMO.

also, in the 2nd conditional you have nested ifs that could be one if with a && and decrease your nesting levels.