Add core.mkdir
Add request_insecure_environment() and secure_trusted_mods
Add fake require() and some package fields
Add io.lines
Remove debug.getlocal

debug.getlocal() can be used to get insecure environments from
calling mods that use request_insecure_environment().
Lua 5.2 is tested
Use fewer macros
Secure create_schematic
Block access to more external files
Rename secure settings