potential path traversal performance improvements

[cyrush]

In conduit::Node and/ or conduit::Schema, there are two basic targets for performance analysis and improvements

• investigate using of char* and direct offsets to avoid string copies during path splitting and path traversals
• investigate reducing the use of recursion for path traversals

Note: The current code was written in a style with correctness in mind (simple use of string helper utilities and use of recursion). Performance hasn't been a bit issue to date, but I am sure there is room for improvement.