[ButtonTrigger]: remake

[IohannRabeson]

The current module is obsolete since Rack 0.4.0 and the stackable wire feature. So this module need to be improved:

• [ ] one button per output
• [ ] one label per output (require to implement a new widget?)
• [ ] one knob to define the value for per output
• [ ] one button to select the mode (continuous / trigger)

The old SVG panel is ugly and the DPI should be adjusted (see API change thread).