Add a graduationRequirement
Rename Xcode's build paths to Makefile and Xcode
Ignore .xccheckout files
Ask Xcode to take snapshots automatically
Remove some pointers
Major shouldn't need to clear the record
Use the range-based for-loop in Major::parse
Inline requirement creation in Major::parse
Return the actual requirement, rather than a copy (from Major::get*Requirement)
Add some blank lines to Major for readability