Fix wrong error logging
Fix #1782

Must use extern "C" otherwise C functions are not linked with the build when called from Objective C++ (.mm) files
Rename data source method implementation to match the one in the protocol.
Fix RKMappingOperation skipping validation when data source tells it to set unchanged values.
Using proper error field for warning
Merge pull request #1799 from RyzacInc/FixUsingProperErrorField

Using proper error field for warning
Add Git submodule step to Testing README.md

fixes #1800
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Added missing init call.
Merge pull request #1810 from matej/initFix

Added missing init call
Fix typo in documentation for RKManagedObjectRequestOperation related to Fetch Request Blocks and Deleting Orphaned Objects
Merge pull request #1814 from obuseme/development

Fix typo in documentation for RKManagedObjectRequestOperation related to...
Prefer the use RKAttributeMapping value transformers if provided instead of defaulting to ones from RKEntityMapping

When using custom RKValueTransformers with RKEntityMapping they are ignored during mapping. With transformed identification attributes this leads to duplicate records.
Changed mapping operation to use transformers provided by attribute mapping, if any.
Unbraced conditional in 1 line
Added test for custom value transformer on identification attribute
missed copying over sourceToDestintationKeyTransformationBlock
Add a CONTRIBUTING.d
More C headers that make the link fail when included in Objective C++ files (#1782)
Test for C headers in Objective C++ files (#1782)
Use custom date formatter on attribute mapping when available