Python support: merge duplicated code

[agarny]

As a result of our Python support, some bits of code had to be duplicated (yuck!). One such code is the one for opening a simulation. Indeed, that code can be used either from our new Python Console window (in which case, it will involve our Simulation Experiment view, if it is loaded) or from a standard Python shell (see here and here, respectively).

Now, as might be expected, there is quite a bit of overlap in that kind of code, which in turn means that it could potentially cause problems when it comes to maintenance (easy to forget to update the "duplicated" code). So, to solve that problem, we should rely on inline code (as we are already doing for our CLI/GUI utilities; see here for example).