New class, MyMemberId. Singleton and pimpl combined! A unified place for the member id to be looked for (without passing an object all over the place).
store, storeAsBestVersion, erase, and find for DataChain. Will manage storage of multiple versions of same file.
Some aggressive (perhaps *too* aggressive) logic to flag a file write as "clobber all existing versions, thanks"
Updating IDataStore interface to return a vector of readers when a version is not specified. RamDataStore's implementation is currently a stub.