Auto-recover last track instead of asking

[merlos]

Change current behavior of the app.

Currently, when there is a track that has started, it asks if you want to load the track of start a new one.
A better approach is to just get back the app in the last status it was when it was closed. Then the user can decide using the standard interface.

This solution gives a more seamless experience and control to the user when making a decision. He does not need to remember what the heck he was doing when the app was closed or crashed, he can see it.

In addition, to complement the feature: add the name of the current gpu file somewhere at the top bar.