gui settings: drop default choices if outside of range

finally finishing this long time TODO now that there is a need with the DELPHI.
gui settings: skip children VA to display

now that .children is a VA, the default behaviour is to display it in the GUI,
but that's not a good idea, so hard-code this VA as not to treat.
odemisd: don't complain about components having multiple parents if one of them is Microscope

Pretty much any component has Microscope as parent, and we know for sure that
it will never create its own ones.
So components created by delegation are always created by the other component.