NDEFRecord

Edits and updates to NDEFRecord and subtypes

Removed recordType enum
Added TNF enum

Group NDEFRecordText, NDEFRecordURI and NDEFRecordSmartPoster into Well-known section
Edit NDEFRecordMedia
Add NDEFRecordExternal
Add NDEFRecordAbsoluteURI
Add example code
Add section about chunked records