PHP can't handle having arrays/objects or functions as keys in its
arrays, so make sure we don't try to pass them from Lua. Booleans aren't
really well-handled either, so let's disallow them too.
Also, add tests for proper stringification of floats and infinities when
those are used as keys.
Note this behavior change is needed to match the change in LuaSandbox
for fixing bug 54527, but isn't itself a security issue.
Change-Id: I1e2951bbe8cb78358650ad377bf7119fcac4485d
Rework the LuaEngine tests to be entirely modular, so that every library
need not add itself to one monolithic file. This also allows other
extensions that add Lua modules to make unit tests without having to
somehow inject them into a test class owned by Scribunto.
The approach taken is similar to that used for Selenium for running
tests against multiple browsers.
Change-Id: I294b2a8195759c0e4fa211f879305a8eb66d9c9a
