On desktop, resetting the model is realized by generating a new
model object. This is due to the fact that we have two different
models (tree and list) and for switching between those, we have
to create a new object.
On mobile, currently there are no plans to support the list-mode.
Therefore, there is no reason the recreate the object. Instead,
implement a reset() function that reloads the core data.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
7e12ac262b