New features

• Add a way to disable LV2 at runtime with SCORE_DISABLE_LV2 (as currently LV2 is broken on Arch Linux)
• Implement mouse and key input for the Window gfx device. Fixes #395

Bug fixes

• Fix some issues with cable deletion order when closing a document
• Fix various nodal process issues
• Improve OpenGL version detection
• Fix .score file association on macOS
• Fix various VST execution issues, in particular with all notes off messages
• Clamp opacity between [0; 1] in relevant text and image processes