Change buildslave's testPunctuation to not depend on the platform

As a side effect, it now effectively checks that individual arguments are
passed properly, instead of just verifying their concatenation.
Merge testMultiWordCommand and testPunctuation into a single test

Since they're about the same thing, really.
Merge pull request #1245 from SpecLad/punct+

Change buildslave's testPunctuation to not depend on the platform