HQPlayer 4 Embedded 4.19.1 released.

Added configuration for volume control range to the web interface. Quick pause option to use old style simple silence pattern for quicker pause in some cases. Short buffer option to use half size FIFOs for reduced delay. Alternate optimizations for various algorithms on Ubuntu and HQPlayer OS builds. Ubuntu Bionic build tested also on Ubuntu Focal (20.04 LTS). Small bug fixes and improvements.