Refactor Properties & References dialogs

Reorganize the methods in the properties/reference dialogs to follow the following order:

1. Class is initialized: All attributes are set in this stage
2. Widgets are initialized: All widgets are configures, labels are set etc
3. Signals are initialized: connect buttons, etc
4. Actions are initialized: connect actions. (Does not affect the current MR)

Logic is mostly the same.

Removed all references to this module from the outside, with the exception of the one button which opens the respective dialogues.

All methods are now private.

Additionally, fixes #248 (closed).