File splitting, C dev version

Both languages now use size_t for the size and indexes in the files.
C++: Insertion sort has been split into 2 files, using the export
keyword (C++11) if it is defined, and #including the .cpp file if it is
not. The same has been done to quicksort.
C: These files are a non-functional development version, and while they
can be tweaked, they should not be used as they are.