Updated plugin version to 1.7.0

Updated version to 1.6.0

Updated version to 1.5.0

Fixed possible upgrade issues.

Updated Demo1 scene with better examples. Fixed bug with SignalDebugg…

…er where signals without arguments throw errors.

Updated README.md for new Signal Debugger panel.

Fixed bug where generating or clearing a Signal Graph would crash God…

…ot 4.2 snapshot 5.

Removed SignalVisualizerManager autoload. Functionality has been move…

…d to SignalVisualizerDock. This will reduce the complexity of integration.

Updated README.md for new functionality and added Troubleshooting sec…

…tion for known bugs and suggestions.

Added icon for Godot Asset Library