Fix mounted order

[jstarry]

Fixes: #896

Problem

Parent and children components rendered out of order. The intended behaviour is that mounted is not called on a parent component until all of its children have been rendered.

Broken Scheduler Queue Order:

1. Create Parent Job (creates and renders component)
2. Mount Parent Job (calls mounted())
3. Create Child Job
4. Mount Child Job

Since the jobs were processed out of order, the child NodeRef was not initialized early enough and therefore not accessible to the parent when mounted() was called.

Changes

• Split scheduler into 3 job queues (comp creation, comp mount, and default (main))
• Always process create jobs first (allows depth first rendering)
• Then process mount jobs in the reverse order they are queued (to ensure root is mounted last)
• Process main queue last (prevents update messages from getting processed before a component is mounted)
• Fix bug preventing node refs from bubbling up if a component renders a node tree with a root node that is also a component. This bug is fixed by linking node refs

New Scheduler Queue Order

1. Create Parent Job (creates and renders component)
2. Create Child Job
3. Mount Child Job
4. Mount Parent Job (calls mounted())
5. Process other messages