NEW: A text entry allows adding signals by name. This includes vectors
not in the signal list, which is useful for plotting calculated vectors
like `let AB=V(a)*V(b)`. It's also a faster way to add a signal if you
know its name already.
Fixes: lp:1851373
* https://bugs.launchpad.net/kicad/+bug/1851373
Improve dialog layout and fix UI policy issues with all of the dialog
boxes in the common, 3D viewer, CvPcb, and Eeschema code paths.
Updated the use of component to symbol.
Jeff Young
Jonatan Liljedahl
Wayne Stambaugh
jean-pierre charras
Maciej Suminski