Apply sensible defaults when creating new idnodes

[adamsutton]

Currently fields have no defaults, this requires lots of altering things that should not need altering. And can cause some confusion.

This is particularly true when creating muxes and satconfs.

[clandmeter]

+1

[adamsutton]

I have added the mechanism and changed some defaults. I think there will be some things that still need changing. I think I might have gone a bit far with AUTO settings in tuning params (particularly for the modulation).