Support start block method in app

[jasonrclark]

Runs after main block processing has concluded for app.

For example this app:

Shoes.app do
  para "before?"

  start do
    para "in the start!"
  end

  para "after!?"
end

Looks like this (not "in the start!" is after even the para that follows the start call):

First of the things in #1200.

[PragTob]

Thanks a lot! =D

great test to think of that edge case!

sorry for the tardiness, been sick :(

[jasonrclark]

Thanks for the merge! Feel better and no rush!