Refactor simulation components

[wawuwo]

Hi!

I started working on #730 and found out that in order to fix it it's better to refine components inheritance hierarchy a bit, so I've come up with this. A short description of changes:

1. Distinction between drawing of simulation and usual components

if (Model.at(0) == '.') {   // is simulation component (dc, ac, ...)
    drawSimulator(p);
} else {    // normal components go here
    drawUsual(p);
}

is removed from Component in favour of a single method — Component::drawSymbol. By default it draws a usual component and anyone wanting their own logic has to override it.

2. A new class SimulationComponent is added: it inherits from Component overriding its drawSymbol to provide logic specific to simulation components. This class is meant to be a common base class for all simulation components.
3. All simulation components are changed to inherit from newly created base class .

There are a lot of commits, but most of them are tiny, and the most important ones are the first two. They lay the foundation for all subsequent ones.

[wawuwo]

There is a problem: with some fonts simulation "box" has wrong size; working on it

[wawuwo]

Now it's OK I hope

[ra3xdh]

I didn't find issues with this PR. Merging. Thanks for the contribution!