Component retention across projects

Components are retained across projects when the split canvas view is used. An example can be seen below:


**How to recreate**
1. Open GUI
2. Press the `View->Split canvas` option
3. Set a component as the active component in one of the views
4. Open another project (either an existing or a new one)
5. Press the `View->Split canvas` option again
6. See that the component previously set as the active component reappears in this unconnected project

**Possible cause**
I personally think that this issue is due to the canvas not being re-initialized/properly cleared when a new project is open.

A good solution would be to completely re-initialize this part of the UI when a new project is opened. This is probably best to do AFTER the simulation functionality is merged in (see #82 ), as it was suggested to separate the editor and simulator in two separate scenes/stages (see #121 ).

Having this separation would make it easy to ensure that all the elements of the previous project are removed from memory.