Modernization
Removing the OS X app demo
Rename ERR macro to DD_ERR
Fixing static analyzer warnings
Add an alias for `l_if`
Correct conditional on DD_ERR macro
Make the DDMathParser header more universal
Fix a couple of build warnings
Fix some logic errors around resolving unary operators
Delete an extraneous file
Merging in janx2/1.1
Updating the rest of the unit tests to use XCTest
Don't use `NSLocalizedDescriptionKey`, since the errors aren't actually localized. Fixes #59