New release 0.3.0

• Replace timer library with calloop::sources::Timer (fixes #13)
• Refactor wpaperd to use wayland-rs 0.30 and latest smithay-client-toolkit
  (fixes #14)
• Do not crash when a new display is added or removed
• The wallpaper duration setting is now more reliable
• Fix panic when a directory is empty (fixes #27)
• Remove output-config from config
• Remove --config argument from cli
• Rename wpaperd.conf to wpaperd.toml and output.conf to wallpaper.toml
  (fixes #25)
• Cleanup code