Implement +storageBehaviorForPropertyWithKey:
Move property key reflection to +initialize
Negate spec description
Defer reflection
Document property storage behavior
Improve documentation of MTLModel
Rename generateAndCachePropertyKeys method
Improve documentation of MTLModel
WS
Pass in attributes to determine storage behavior
Look up associated objects less frequently
Remove attribute argument
Fix TomDoc style
Only consider weak properties transitory
Merge branch '2.0-development' into property-behavior
Consider weak properties permanent

Until we find a way to reliably detect readonly weak properties
:cry:
Merge branch '2.0-development' into property-behavior

Conflicts:
	MantleTests/MTLTestModel.h
Allow subclasses to override +propertyKeys
Fix accidental use of -isEqualTo:
Use -isEqual: