Support lua-TestMore Lua implementation test suite

[agladysh]

http://fperrad.github.io/lua-TestMore/

This is a good and well-known test suite for Lua programming language implementations. (Note that the test suite is hiding behind Test::More port to Lua, don't be confused by that.)

I see that the Moonshine has its own tests, but it is not exactly the same thing. IMO, it will be very nice for the Moonshine to publish how well it passes lua-TestMore tests, as it will illustrate how well it conforms to the language standards.

Would be also cool to have a a coverage report — like this one:

http://fperrad.github.io/lua-TestMore/cover_lua515/src/index.html

Note that it is usually OK to have small deviations from other implementations — especially in gray or unspecified areas, like this:

https://github.com/fperrad/lua-TestMore/blob/master/test_lua51/014-fornum.t#L92

lua-TestMore author, @fperrad, in my experience, usually reacts quite well to the pull requests, feature requests etc., so I encourage you to cooperate with him in getting this thing working. I'm sure he'll be OK with adding the Moonshine as yet another "target" for his suite.

[paulcuth]

Cheers for this, btw. It's massively useful and i've been working on getting Moonshine passing as many as possible since the weekend. I'll report back when I'm happy I've picked off all the low hanging fruit.