Because the *pb.go files get auto-generated, we can't easily
keep the license block on the top of the *.pb.go files.
Instead, we keep a copy of the LICENSE file in the same directory
as the generated *.pb.go files.
NodeState is shared among nodes in the cluster (via gossip
in a gossip implementation) and cached locally in Cluster.Nodes
in order to be available to the /status endpoint.
this affects the scanner/parser and makes it produce signed ints rather than
uints, and so it affects all code that is expecting unsighed ints to come out of
the parser.
Previously the cache type (`lru` or `ranked`) was determined by
checking the ending suffix of the frame. If it ended with a `.n`
then it was ranked. Otherwise it was an LRU.
This commit changes frames so that a `cacheType` option can be
passed in during creation to set either `lru` or `ranked`.
