Initial import of a set of PRNG test programs from Bob Jenkins
Added CMake support and fixed all compiler warnings
Added LICENSE.txt
Moved the PRNG implementation from rngav.c into a separate file

Also generalize it to support arbitrary number of bits per
term (up to 64 bits) and generation of a reverse sequence.
But this incurs some performance penalty.
Plug the newly separated PRNG implementation into the countx test
Plug the newly separated PRNG implementation into the freq test
Plug the newly separated PRNG implementation into the chi test