Fix overwritten debug tools

[Vadi]

In the current release of Mudlet, the whole set of debug functions is overwritten by one useless function in Mudlet by accident. This'll most likely be solved in a future update, but for now you can simply do:

Code: [show] | [select all] lua

debug = require "debug"

To fix this.

Things like debug.traceback can be quite good to place in scripts at erroneous places