(fixed) ESB testing and filenames

[kaypy]

While I'm submitting stuff anyway.

ESB will happily load a file that isn't named dungeon.lua

But if you try to test it, then the temporary file will be named something like notdungeon.lua.testing

And then the DSB link will fail to find it.

Either DSB should load whatever filename ESB uses, or ESB should use dungeon.lua.testing regardless of the original filename, (or I should stop using weird filenames)