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* Document how to get all entries in ranger
* update doc + test

* Add Len() to Ranger

##Summary
Investigated memory leak symptoms reported in #15 , and turns out path compression upon removal of networks was not implemented correctly, instead, it simply did a parent child reassignment.

Added to unit testing to prove desired behavior and added a memory leak unit test using a slightly modified version of the test used to uncover the problem in #15 , use -short flag in local testing to skip added slow test, as documented by https://golang.org/pkg/testing/#Short

Signed-off-by: Rob Adams <readams@readams.net>

* Search by CIDR rather than just by IP.
Signed-off-by: Rob Adams <readams@readams.net>

Fix index-out-of-bound bug when inserting network that shares direct branch point with single-IP (leaf) network, closes #3

Support storing custom user data with inserted entries to Ranger by introducing the RangerEntry interface, closes #2