Don't require new project dialog

[Laszlo Pandy]

Like most other document oriented applications, we should start with an empty project. This allows the user to start working right away. The New Project dialog only acts as a barrier to doing work.

The technical reasons for this dialogs existence is that we need to create a project folder to store imported and recorded audio. Jokosher should have a directory ~/.local/share/jokosher/emptyproject/ where it can store these items. When the user clicks save, they will be given the save as dialog just like in every other document oriented application.
The audio files will then copied to the new destination.