Updates to the embedded radix tree: generalization and testing.

- Added functions for most node-specific operations
- split out leaf-level operations, and node-level ones
- provide a set of default functions
Merge pull request #72 from interwq/master

Multicore update
merge Qi's code
Merge pull request #74 from interwq/master

Fixed Makefile to detect number of sockets
Merge pull request #75 from ryuxin/master

merge Qi's code and remove warnings
ertrie enhancements and cleanups:  split functionality into pointer-based kvtrie, and embedded structure ertrie.h.
Merge branch 'master' of github.com:gparmer/Composite