Comment 10 for bug 497164

Taking Matthew's idea to the next level:
Have explicit dependencies.

 1. Decide whether to paint table blue or red
 2. Buy paint (a)
 2. Buy brushes (b)
 2. Buy drop cloth (c)
 3. Paint first coat on table

would mean:
- 2a, 2b, 2c depend on 1.
- 3 depends on 2a, 2b, 2c

Pro:
- Very flexible, could even allow to depend on tasks not in the current "main task". For example all the 2* tasks could depend on "create money".

Cons:
- Needs loop detection. ("A depends B, B depends A" <- not good!)
- Selecting the task to depend on might be a UI challenge.
- "Display Sorting" according to a directed graphs isn't straight forward either