Build and testing system needs an overhaul

[TheCount]

While preparing #16, I noticed that the build/testing system is a bit onerous to work with. Specifically, the various *.in files appear to be some intermediate products (from autoconf?), probably the result of YAEP being part of a different software suite before it was split off as a standalone package. A particular headache were the bulky *.tst.in test files.

So before I continue working on #12, my next step would be to overhaul the building and testing process. I'm thinking CMake/CTest: it's compatible to more environments than autoconf, supports separate out-of-tree builds for C and C++ easily, and is generally less pain to work with. I'll also split the *.tst.in files into smaller files and put them in a separate directory.