Modify Lua module loader to trace each file as it's executed

[naturallymitchell]

If we can prepend every Lua file Torchbear runs with

log.trace("running: " .. debug.getinfo(1, 'S').source)

Then it'd be much easier to debug.

Since bridge.lua already sends off into the app, I think we'd have to modify the package searcher to basically do standard require(), but just add that one liner ahead of the module to run.

Possible?

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or add need, use, or run instead of require

[naturallymitchell]

use _require() for original function

[Arnaz87]

replace the global require function to a function that first logs the required module, and save the original require in _require