Fix debug build to address issue #10

Travis fails to build on gcc due to wrapping.  Creating PR in the meantime since issue is unrelated to this fix.
Any plans to consolidate the checks since they seem identical. Also if you provide an optional output string argument to the `bool isValidInertiaMatrix()` could you return the message returned by the exception thrower? If the checks are improved/extended I would hate have yet another copy of inertia checking to be updated.