Maintenance Release

• Add command/binding to jump to currently playing track (fixes #181)
• Add OpenUri D-BUS MPRIS support (#185)
• Implement volume normalization setting (fixes #195)
• Implement audio_cache setting (fixes #196)
• Support configuration of audio backend and backend device (fixes #194)
• Handle lost/disconnected sessions gracefully (fixes #34, #125, #176, #192)
• Add configuration value to drop default keybindings (fixes #204)
• Only clear credentials when they're invalid (fixes #77)
• Add noop command to override single default bindings (#207)
• Add help command (#208)