No path to use sequencing functions of SignalIO Devices

[nicost]

While trouble shooting an issue with the NIAnalogOutPort, I realized that SignalIO device implement sequencing functions. However, MMCore offers no functions to make use of those sequencing functions (unless I am completely overlooking things)..
We should either remove these from SignalIO, or add the corresponding functions to MMCore (which must have been the original intent). Thoughts @marktsuchida ?

[marktsuchida]

[Reminder, including to myself: SignalIO, despite its misnomer, is actually "analog output" (plus blanking). (Analog input devices are typically Generic devices with a property showing the voltage.)]

The sequencing functions in SignalIO are already used, in the various Utilities devices: DAZStage, DAXYStage, DATTLStateDevice, and MultiDAStateDevice. These work with MDA and the state devices support blanking (I think). If we add direct functions to control SignalIO sequencing, there are two problems: (1) they won't work with any existing MDA engine, and (2) the gating (blanking) functionality won't work. Of course, they may still be useful in some (scripting) situations.

So the question is: what do we need these functions for, and what would code using them look like?