Changes

v1_17 part 1: duplicate the 1_16 folder
 (commit: 9c9fe57)

v1_17 part 2: version bumps (Denizen 1.2.1)
 (commit: 51b0ba2)

v1_17 part 3: automatic import swap
 (commit: aca6053)

v1_17 part 4: rename files too oops
 (commit: e98e140)

v1_17 part 5: nms import corrections
 (commit: 4c2bb3f)

v1_17 part 6: begin changing to mojang mappings
 (commit: b43d9be)

v1_17 part 7: first sweep of mojang mappings changes
 (commit: 931a644)

v1_17 part 8: third pass of mojang mappings
 (commit: b0ce228)

v1_17 part 9: fourth sweep of updates
 (commit: 91d3789)

v1_17 part 10: final sweep of updates - it compiles!
 (commit: 435c3c5)

v1_17 part 11: redesign reflection handling
 (commit: b06fa63)

additional fixes from testing
 (commit: d73c239)

use new core adjustable#safeAdjustDuplicate to fix fakespawn mechs
 (commit: 6537fa4)

fix hover item backparsing
 (commit: 5ea333a)

add workaround for spigot 1.17 remap error

https://hub.spigotmc.org/jira/browse/SPIGOT-6550
 (commit: 431469f)

packet interceptor late loader
 (commit: a6f0f85)

fix sync of attach to a vehicle's passenger
 (commit: bc766d1)

debugblock command
 (commit: f03d486)

fix horse jump event

and some 1.17 stuff and some meta
 (commit: 090d57a)

LocationTag.find_nearest_biome
 (commit: 270dd47)

fix up sidebar impl for 1.17
 (commit: 0c29de7)

fix npc sneak nms logic
 (commit: 1bd6c9a)

EntityTag.last_hurt_by mech
 (commit: a0bf726)

patch walk command with vanilla mobs in 1.17
 (commit: 88a68b9)