Watching Several Changes With One Listener:
$watchGroup
Making A Child Scope
Attribute Shadowing
Digesting The Whole Tree from $apply and $evalAsync
Destroying Scopes
Update CONTRIBUTING.md
Update README, fix contributing url.

The case was important here :P
Setting Up The Infrastructure for Watching Collections
Detecting Non-Collection Changes
Handling NaNs in $watchCollection
Detecting New Arrays
Detecting New Or Removed Items in Arrays
Detecting Replaced or Reordered Items in Arrays
Array-Like Objects
Detecting New Objects
Detecting New Or Replaced Attributes In Objects
Detecting Removed Attributes In Objects
Preventing Unnecessary Object Iteration
Dealing with Objects that Have A length
Handing The Old Collection Value To Listeners