Imported FRBAttributedStringBuilder class with tests.
Updated FRBAttributedStringBuilder to use modern Objective-C syntax where appropriate.
Added FRBDiff folder structure and some template files.
Added trivial test cases for FRBDiff.
Added simple dictionary-dictionary diff implementation (without traversing key paths).
Added functionality to recursively traverse key paths and return these in diffs.
Merge branch 'feature/FRBDiff' into develop
Updated pod spec and header files so that it is safe to import any header and only the existing ones depending on the podfile configuration will be imported.
Updated podspec so that the generic header files are always included in subspecs.
FRBAttributedStringBuilder is no longer a singleton (but a default singleton instance is provided if needed).
Added FRBAttributedStringBuilder to podspec.
Merge branch 'develop'