Rewrite permissions plugin in C++

[vexyl]

The permission system should be a core part of the server and should be rewritten in C++.

[vexyl]

Also, plugin writers should be able to use permissions and groups easily. They should be able to create permissions and groups on the fly under some common name of the plugin writer's choosing (use std::map).

Worlds should be able to create its own permissions and groups easily using the above idea. E.g., worlds could have a group called admin (with world permissions visit,build,modify) that can build even when the owner sets a build limitation.

Pseudo code:

Server.RequirePermission("essentials.world")
world.RequirePermission("build")

Server.RequirePermission = 
    MakePermission("server", permissionName)

world.RequirePermission =
    MakePermission("world_" + world.GetName(), permissionName)

[vexyl]

Example of how the permission configuration files could look:

---permissions.ini---
[vexyl]
permissions=permissions
groups=admin,server
primary_group=admin

---groups.ini---
[admin]
color=&c
permissions=essentials.kick,essentials.ban
inherits=builder
canPlaceBedrock=true

[server]
color=&e
permssions=essentials.server
inherits=guest

[builder]
color=&b
permissions=essentials.cuobid
inherits=guest

[guest]
color=&9
permissions=build,talk,interact

[GiantCrocodile]

The permission system should be:

• able to log any permission violation (user x tries to do an action which requires permission y but the user doesn't have permission y) to a file
• not being in Lua plugins nor the Client classes
• prevent permission names conflicts by not allowing duplicates (could be achieved by prefixing every permission with the plugin name and check if a plugin registers same name twice)
• prevents usage of blocks listed in a bad blocktype enum (like TNT, bedrock, etc.) without correct permission

[GiantCrocodile]

• have a placeable blocks option that has a list of blocks (not one option for each block)
• having the permission system handle all permission checks (including checks for placeable blocks)
• groups should be written in C++ too
• operators should be optionally disabled
• log all permission changes

[GiantCrocodile]

We need two kinds of security layers for the permission system:

1. first layer is checking if a plugin is allowed in general to call a specific function of the Core
2. second layer checks if an user has the correct permission to call the plugins command which calls then a Core's function (which is protected by Layer 1)