Post-mortem

[shrekshao]

• finish the draw model func with multi hierachy model (directly copy and adapt from forward-plus shader)
• add depth of field to the effects feature list in instruction
• further refactor the structure? split the setup for each pass into different js file just as it is done in forward-plus shader? (Though I think Kai's better at design, but it may be more difficult to understand at the start)