v7.2.0rc0

• ADDED: Driver information section to documentation
• CHANGED: AppPLL settings updated to reduce jitter (#112)
• CHANGED: app_usb_aud_316_mc: Improved DAC configuration sequencing
  following datasheet recommendations
• CHANGED: app_usb_aud_316_mc: Manual DAC setup rather than using
  auto-config to improve output quality (internal PLL no longer used)
• FIXED: app_usb_aud_316_mc: Intermittent output from DACs due to DAC
  auto-standby (#110)
• FIXED: app_usb_aud_216_mc: Define app defaults ahead of lib_xua defaults
• Changes to dependencies:
  • lib_xua: 3.3.1 -> 3.4.0
    • ADDED: Unit tests for mixer functionality
    • ADDED: Host mixer control applications (for Win/macOS)
    • CHANGED: Small tidies to mixer implementation
    • CHANGED: Improved mixer control channel communication protocol to
      avoid deadlock situations
    • CHANGED: By default, output volume processing occurs in mixer task, if
      present. Previously occurred in decouple task
    • CHANGED: Some optimisations in sample transfer from decouple task
    • FIXED: Exception on startup when USB input disabled
    • FIXED: Full 32bit volume processing only applied when required
    • FIXED: Setting OUT_VOLUME_AFTER_MIX to zero now has the expected
      effect
  • lib_xud: 2.2.1 -> 2.2.2
    • FIXED: Syntax error when including xud.h from C
    • CHANGE: Various API functions optionally marked as a weak symbol
      based on XUD_WEAK_API