Basic security in place.  The Admin user must provide a valid password
to start the server.  The SHA256 hash of this password is stored in
plain text in the config file.  All logbases created by this server
include this user.  The server creates and uses a ServerUsers logbase in
its basedir which will be used for logbase-level security.  Not sure if
I want record level security, still thinking about it.

Split Listen and Serve steps in order to allow the server to be
gracefully shut down when a .close file appears in the invocation
directory.

Implemented multiple value types, with a value type integer inserted
into every value.  This allows large internally structured blocks of
data to be saved as a file elsewhere, with the logbase storing a file
path (among other benefits).

Gave some thought to supporting key types other than string, mainly to
make for more efficient storage and access to large numeric data sets
such as time series.  Leaning against this.