2021.17.0

• Move to Pl3x DL API V2 (#977)
• fix: SPIGET_RESOURCES not always downloaded (#975)
• Update Airplane branches for 1.17 release (#968)
• Simplified and improved multi-version handling for Fabric #964
• Bukkit/Spigot download URL switched by VERSION #962
• Update start-deployAirplane (#960)
• Correct AirplanePurpur branch name (#936)
• Move to new Airplane download system (#933)
• Fixed issue with unset FORCE_REDOWNLOAD with TYPE=AIRPLANE #979
• Updated getbukkit download URL #958
• Don't echo double-double-quotes to server.properties (#954)
• Fix unquoted COPY_MODS_DEST and COPY_CONFIG_DEST variables (#942)
• Allow to enable the whitelist without modifying the whitelist file (#937)