Test dev 0.4.0 round 1

[MartinHjelmare]

• Add api image event repr.
• Add sample event repr.
• Clean up center class repr.
• Add enabled state to automation repr.
• Fix removal of event handler.
• Set default image data values upon file error.
• Fix dict comprehensions for images.
• Fix event data matching.
• Handle all zero pixel images.
• Turn off interactive backend to avoid tkinter requirement.
• Add action to send multiple commands.
• Make rename image more robust.
• Add z index image slice as image event property.
• Make gain setting more robust.
• Wait for scanfinished when stopping leica imaging.