Improvements to BSD-licensed DTC.

• Numerous crash and bug fixes
• Improved warning and error messages
• Permit multiple labels on nodes and properties
• Fix node@address references
• Add support for /delete-node/
• Consume whitespace after a node
• Read the next token before the second /memreserve/
• Fix parsing of whitespace
• Clean up /delete-node/ and add support for /delete-property/
• Handle /delete-node/ specifying a unit address

Obtained from: https://github.com/davidchisnall/dtc @df5ede4