Tentative steps towards single-header-file-ification:
 - Moved all C code into the header file. Only defined if ALGO_IMPLEMENTATION is defined.
 - Decorated all function prototypes with ALGODEF, which can either be static or extern based on
   whether ALGO_STATIC is defined.
Oops -- don't hard-code the random seed!
Use some MSVC CRT debug functions to verify heap integrity after every test
AlgoQueue and AlgoHeap no longer call malloc() internally.
Don't need string.h