radix-tree: major cleanup
radix-tree: adapt defines to the new tree design
radix-tree: removed unused function, adjusted structure to the new tree design
radix-tree: fixed compiling issue
radix-tree: initial implementation of the new insert function

Lots of things are still missing.
radix-tree: fixed var naming
radix-tree: better debug message
radix-tree: implemented prefix_mismatch function