Minor: Cleaned up InchCoord/Location headers

• Removed blank lines from InchCoordish and InchLocationish protocols in order to make them more compact.
• Moved the doc comment for nsValue from InchCoordish to InchCoord.
	» We the main model class to be authoritative.
• Added nice, clean Apple-doc-style section headers “Property Access”, “Convenience Access”, and “Explicit Manipulation” to InchCoord's and InchLocation's interfaces for, respectively, the “true” properties, the NS/CG convenience getters, and the manipulateAs…: methods.