initial attempt at a unified interface to signal buses

[superwhiskers]

an attempt at providing an interface to signal buses on components

closes #190

checklist

• All tests pass.
• Code compiles cleanly with flags -Wall -Wpedantic -Wconversion -Wextra.
• The new code follows GridKit™ style guidelines.
• There are unit tests for the new code.
• The new code is documented.
• The feature branch is rebased with respect to the target branch.

[shakedregev]

This seems easier from the user perspective compared to #199. Let's make sure this runs smoothly.

[superwhiskers]

this is probably ready for review now. i don't think changing constructors is appropriate just yet. doing that will be more appropriate when they way they're handled in the json format / data model is worked out. all this pull request does is unify the way components handle them internally, in preparation for a more involved change.

[pelesh]

this is probably ready for review now. i don't think changing constructors is appropriate just yet. doing that will be more appropriate when they way they're handled in the json format / data model is worked out. all this pull request does is unify the way components handle them internally, in preparation for a more involved change.

You just need to modify genrou and tgov1 data structures. We can assemble them manually, without a parser in an example. With Genrou and Tgov1 constructors taking in the data structures and initializing signal connections, this PR will be ready to merge.

Other than that, this is very nice work and the code is clean and readable.

[pelesh]

lgtm