Add a debugging function to print the parsed argument list.
Do the easy stuff:  replace printfs with std::cerr, and strlen(x) with std::string(x).size().  This seems to have fixed the memory diddling in issue #102, although i didn't see an obvious reason why.
Fix the memory-diddling bug (issue #102) by using std::strings for all the argument  text-strings. Also update a few operations done on char-array to operate directly on std::strings.

Edit main.cpp to be compatible with std::strings from arguments struct.
Merge branch 'feature/RPL_command_line' into develop

Tidies up CommandLine.{h,cpp}, eliminating almost all c-strings. Fixed uninitalised-memory bug.