Made single panel mode not ever load data into the second panel (memory optimization)
Made the thumbnail widget let go of the memory of the model when the window is closed.
Put in an explicit DeletFileFromSdCard
Turned some bools into enums for clarity
Broke some of the print leveling wizard into separate files.
Started work on a new 2 point probe (actually an n point switch -> bed position maper).
Refactored a bunch of file names and other data.
The QueueData and the LibraryData are practically the same class and shoud
be shared as we move the QueueData into the data base.