Plugins Audio Scrubber

• Fixed compatibility issues with VaM 1.21 and 1.20; now requires 1.20 or newer instead of the latest (1.22)
• Updated the source files to depend on my custom "common library" for general plugins - on the user end, this only shows up as very slight usability improvements (alert if added to wrong atom type, scrubber selection popup auto-closes when clicking on UI background, and selected option text is better visible)