Attribute parameter substitution patches

[Peter TB Brett]

Stephan Böttcher writes:

> here's a patch to gnetlist that implements parameter substitution in
> hierarchical schematics. The idea is that some attribute values in the
> child page are defined in terms of parameters, that can be substituted
> in individual instances.
>
> A resistor in the sub-schematic may have the attribute
>
> value=$RFB
>
> and the instance symbol for that sub-scematic in tha parent schematic
> may have the attibute
>
> parameter=RFB:12k

He continues:

> a extension of the previous patch to allow parameter names to contain
> digits, and allow references to arbitrary parameter names in ${braces}.

I'm adding a report here because I haven't yet decided whether it's a good idea to pick this patch up.