Radium

Quick release that fixes popup menus in the mixer and freeze when rendering multiple sound files on OSX and Windows (when song has VST or AU plugins).

Changes 5.8.9 -> 5.9.0:

• Soundfile saver: Make the "All files saved" dialog modal, and fix keyboard focus.
• Soundfile saver: Only save audio from current "system out", the one that has slider in the bottom bars.
• Soundfile saver: Option to set number of channels
• Modular mixer: Fix sound object popup menu.
• Soundfile saver: Avoid freezing on OSX and Windows when saving multiple soundfiles.
• OpenGL: Hide Mesa startup warning for AMD devices (Teteros)
• Build: Silence missing libxaw warning (Teteros)
• Build: install.sh script to create radium directory in /opt and other places.