Add new pbxproj parsing logic

This is yet untested logic, but in theory it seems more robust than the old, peg-based algorithm.
Remove old pbxproj parser
Minor aesthetic rearrangement
Add tool to test XcodeKit
Fix crashing bug

I have to effectively disable the charactersToBeSkipped functionality so that the whitespace-skipping functionality works as intended.
Improve error reporting
Typo fix
Fix new pbxproj parsing logic