Most stuff here was recently changed. Some of it was where I found a pattern in something that was likely copy-pasted from somewhere else, so I did a global search and replace on that.
Contributes to issue CURA-5784.
several instances need to be created.
- In the ThreeMFWorkspaceReader we need to create some temporal
instances of Preferences that makes it not singleton anymore.
- The current preferences are kept in the Application class and so all
the calls to the preferences are changed to get the preferences from
Application.
- The method getInstance in Preferences is kept as deprecated since some
external plugins.
