Remove .leaf and create Leaf() method

Do() traverses the tree, correctly and Insert() will not
create bogus branches.

Remove() is still a mess
Merge pull request #2 from abh/master

Add failing test case
not needed, prune starts to work
Simple remove seems working, except when hitting root node
prune starts to work
Removing println
Fiddling with prune(), slowly getting there
Holy cow -- seems to work
Implement remove
More function in the 64 variant
Fix parameter lists for radix64 stubs