Improve documentation on closure types.#249

Merged

Havvy merged 4 commits intorust-lang:masterfrom

alercah:closures

Feb 24, 2018

Commits on Feb 20, 2018

Expand on mechanics of closure types.
Alexis Hunt
committed

Commits on Feb 21, 2018

Fix compile errors.
Alexis Hunt
committed

Commits on Feb 24, 2018

Havvy's review feedback on closure types.
Alexis Hunt
committed
Fix colon placement in note.
Alexis Hunt
committed