Place sub-headings under the primary ones
Avoid wrapping code lines
No longer require env-var 'time_unix' for db-update operations

The update routine can use the current system time, so only require the
env-var for (dis)connect operations. This enables the minimal db-update
method to be used by external callers with an implicit time if desired.
Update Readme with info about the partial-update API

This documents the env-var based "manual" method to perform
partial-updates.