add epic luacontroller

[BuckarooBanzay]

With safer_lua:

• Demo: https://github.com/joe7575/safer_lua/blob/master/demo.lua
• Issue: Documentation (oder Schnellbleiche) joe7575/safer_lua#1

[brylie]

This would be really useful since it can be quite tedious to build block-based rules. The lua subset could initially be limited to functions that are used in other Epic blocks perhaps?

[BuckarooBanzay]

another alternative to a full-blown self-made luacontroller would be to include epic as a library into the mesecons LuaC, but that would need minetest-mods/mesecons#557 to be merged first 🤔