Adding NSValueTransformer+MTLErrorHandling
Adding NSValueTransformer+MTLErrorHandling to iOS target
Fixing spec description
Adding error handling support to MTLValueTransformer

as well as existing transformers
Suppress -Wdeprecated-implementations
WS
Add error handling to boolean and URL transformers
WS
Move transformer error handling into a protocol
Adding success parameter to MTLValueTransformationBlock
Adding success paramter to MTLValueTransformer methods
Adding error handling to built-in transformers
Add error handling tests for built-in transformers
Add MTLTransformerErrorExamples to Manle iOS Tests
Fix spelling
Rename MTLValueTransformer methods
Make MTLTransformerErrorHandling.h public
Improve documentation of MTLTransformerErrorHandling
Improve documentation of MTLValueTransformer
Rename MTLValueTransformer class methods