This follows the coding style guideline that the file that contains a
class should follow the exact name of this (main) class.
key.{h|cpp} -> PrivateKey.{h|cpp}
These are technically static libs, but not in any way shared libs.
They are used solely only by this repo and really only by the hub.
Most important, no header files are installed and basically none of
the normal rules for reusable libraries are applied to these files.
tomFlowee