Previously both PeriodicPropertyPublisher and TriggeredPropertyPublisher
published irrespective of the property value.
This change adds an optional epsilon value below which a
notification will not be made. This significantly reduces the number
of Emesary notifications generated and therefore updates to the
displays.
Add Multikey support for the FG1000 (:GF and :GP) to improve useability
by allowing direct entry of strings. This is massively easier than
fiddling with the control knobs.
Also correct interface variable name "frequency" to "period", which is
more accurate.
ConfigStore for storing and retrieving config settings (needs XML import/export)
Header display with 4 different header fields (all configurable)
Publisher for ADC and FMS.
