Reworking schematic equipment mgnt. + Adding shield schematics

[RedstoneFuture]

Goal: The real goal of this PR was to allow the shields to be handled as flexibly as the schematics, to have one or more shields on different maps. This feature has been missing on my server for a long time and is therefore useful in practice.

Overview about the changes:

• Renaming some classes & methods
• Fixing issues in equipment randomizer
• Adding new class structures:
  • MissileConfiguration.java + ShieldConfiguration.java with extends SchematicConfiguration.java
  • Missile.java + Shield.java with extends SchematicObject.java
• Changing default resource shield.schematic to shields.zip with saving to plugins/MissileWars/shields/
• Renaming and Moving old /game/misc/Shield.java to /listener/ShieldListener.java

Misc: Config generation, schematic pasting of missiles and shields, and the equipment randomizer was tested ingame. Facing rotation has only been implemented for missiles so far. This was not different before.

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Most important changes:

I recommend looking at the 6 classes individually. The rest of the small things have been commented individually here in Github.

• MissileConfiguration.java + ShieldConfiguration.java with extends SchematicConfiguration.java
• Missile.java + Shield.java with extends SchematicObject.java

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New Config:

[...]
missile:
  onlyBlockPlaceable: false
  onlyBetweenSpawnPlaceable: false
  northFacing: true
  eastFacing: true
  southFacing: true
  westFacing: true
  schematics:
  - egg: "CREEPER"
    down: 2
    dist: 2
    schematic: "Tomahawk.schematic"
    name: "&aTomahawk"
    occurrence: 3
  - egg: "BLAZE"
    down: 2
    dist: 2
    schematic: "Cruiser.schematic"
    name: "&eCruiser"
    occurrence: 2
  - egg: "SKELETON"
    down: 2
    dist: 2
    schematic: "Sword.schematic"
    name: "&7Sword"
    occurrence: 2
  - egg: "MUSHROOM_COW"
    down: 2
    dist: 2
    schematic: "Juggernaut.schematic"
    name: "&4Juggernaut"
    occurrence: 1
  - egg: "HORSE"
    down: 2
    dist: 2
    schematic: "Piranha.schematic"
    name: "&3Piranha"
    occurrence: 3
  - egg: "ENDERMAN"
    down: 2
    dist: 2
    schematic: "Tunnelbore.schematic"
    name: "&0Tunnelbore"
    occurrence: 1
shield:
  fly_time: 20
  schematics:
  - schematic: "shield.schematic"
    name: "&cShield"
    occurrence: 1
[...]