Refactor Scaling Procedure

[rouille]

We want to refactor the way the grid and the profiles (demand, hydro, solar and wind) are scaled via the change table in the Scenario object.

[rouille]

• Identify all the modules that will be impacted by a refactoring of the scaling procedure.
• come up with a design for the refactoring of the grid. The grid is scaled only once since the MATReader object is now used to get the grid post simulation.
• come up with a design for the profiles. Those are scaled twice, pre and post simulation.
• validate the design with the software team.
• implement the changes.
• write tests.

[danielolsen]

With #186 and #194 in, do we plan to do any more work on this refactor?

[rouille]

This issue was created for @dmuldrew's design of the transformation of the grid.