This was dead code that did never work, and most of it was boilerplate that
you can steel in 15 minutes from any existing math inset. Apart from that it
did contain a pointer to InsetXYMatrix which would create the same problems
we saw with the macros.
This patch puts all projects into subfolders (at least for MSVS). In this
way, there is a better overview (especially if the number of test projects
will be increasing).
