TODOs
----------------------

Most code cleanup things from gschem apply here too

tweak to gnetlist to add `instance-get-pins'

gnetlist gave the coordinates of the component it was unhappy with and
the component type.

Put code in that deals with the opening of a schematic twice... 

Add more regression tests 


Hierarchy support
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OKAY separator configurable (char or string, or nothing)

OKAY append / prepend of tag

FOR DOCS no slotting on composits
FOR DOCS no net= attribute on composites
FOR DOCS hetrogenious slotting works if you have uniq pinlabels

DONE multiple sources for underlying schems

SEEMS TO WORK... many many levels of hierarchy?
MUCH TESTING NEEDED