XC + XV: minecraft guns and vehicles combat

Minecraft guns combat XC and vehicles XV (vehicles depends on guns).

Source structure:

minecraft-xc/
 ├─ docs/                  - Documentation
 ├─ xc/                    - Gun combat
 |  ├─ lib/                - Other .jar, put spigot 1.16.5 in here
 |  └─ src/                - Plugin source
 |      ├─ main/           - Main plugin source
 |      ├─ nms/            - Minecraft version specific source
 |      |   ├─ v1_16_R3/   - 1.16.5
 |      |   └─ v1_18_R2/   - 1.18.2
 |      └─ test/           - Unit tests
 └─ xv/                    - Vehicles