Add layers to document

[KCGD]

Is your feature request related to a problem? Please describe.
Managing, re-arranging and deleting parts of notes is difficult when dealing with very complex / dense notes.

Describe the solution you'd like
It would be helpful to add layers to the notes and be able to select an "active layer" to draw on. This would allow making notes that do not effect other parts of the document and therefore make managing notes in the same document easier.

Describe alternatives you've considered
I usually use the polygon select tool to select the specific parts of the note I'd like to manage.

Additional context
For example: I use rnote to make note sheets for exams at my university. The layer tool would make it much easier to manage lots of information in a confined space.

I'm imagining this would work similarly to layers in image editing applications (photoshop, gimp, etc)