Add new settings to PROJECT_DEFAULT_BUILD_SETTINGS

CLANG_WARN__DUPLICATE_METHOD_MATCH = YES
CLANG_WARN_UNREACHABLE_CODE = YES
[Spec] Don't generate a requirement for each key in settings, but instead for each set of settings

Generate instead more helpful error descriptions.
=> Few stack traces, more overview
[Spec] Exclude expected base settings from built settings for other configurations, so they won't be listed as unexpected
Nest all keys in arrays
Fix extracting key value pairs from xcconfig files

CODE_SIGN_IDENTITY[sdk=iphoneos*] = 'iPhone Developer' was splitted into "CODE_SIGN_IDENTITY[sdk" and "=iphoneos*] = 'iPhone Developer"
[Spec] Fix comparison of array setting values
No special handling for bundle product type
Fix build settings for Xcode 6b2
[Spec] Added a spec for constants
[Spec] Choose other examples to test settings
[Fixtures] Add Project with different targets with Xcode 6b3
[Fixtures] Update fixtures with Xcode 6b3
Fix build settings for Xcode 6b3
[Spec] Rename new spec file
[Changelog] Use two empty lines between each version
[Doc] Add missing parameter documentation to #new_target and #new_resources_bundle
[Doc] Document how to update build settings integration specs
[Fixtures] Re-dump xcconfig files with sorted keys
Add a Command to dump build settings to xcconfigs
[Fixtures] Format changes to match output of the builtin command