Clean up imports.
Enable persistent vanish state for admins.
Fix vanish state bleeding into non-ModMode.
Document why we swap out normal player groups rather than just tagging with the ModMode group.
Fix vanish for admins.
Fix allow flight flag for admins in creative mode.
Ensure that VanishNoPacket is enabled; Spigot doesn't seem to honour harddepend as mandating enable order. Catch an intermittent exception from Player.teleport().
Version 3.0

This version removes dependence on NMS classes and changes the way player
state is stored.  Player data is now stored in YAML files in
plugins/ModMode/players/.  Player attributes are modified exclusively via
the Bukkit API.

This implementation fixes an IllegalStateException in NMS code when
Player.teleport() is called after a ModMode change.  The effect of that
exception was to break Bukkit.getPlayerExact() and led to chunks not loading
for the player.  The problem was most apparent when transitioning out of ModMode
from The End.

To install, stop the server, set an empty list of moderators in
plugins/ModMode/config.yml and copy world/players/normal_<player>.dat to
<player>.dat for all ModMode-capable staff.
Version 3.1

Re-add support for separate ModMode and normal player ender chests.
Remove CraftBukkit from the build time dependencies.
Fix vanish state restoration and visibility to staff.
Attempt to force VNP to correctly propagate visibility state changes. Remove spammy exception trace the first time players use ModMode.
One last try at fixing vanish. More likely suspects: permissions plugin or VNP bug.