Bug 2916

Overview:
The CommandLine parser treats uint8_t as char. Therefore uint8_t variables get treated unintuitively.

Steps to Reproduce: 
1) Create a script that uses a uint8_t command line argument:
int
main (int argc, char *argv[]) 
{
  uint8_t seed = 0;
  CommandLine cmd;
  cmd.AddValue ("value", "Some Explanation", seed);
  cmd.Parse (argc, argv);
}
2) Run the script with the argument "--value=1"

Actual Results: 
cmd.Parse (argc, argv) sets seed to 49, because 49 is the ASCII value of character '1'.

Expected Results: 
cmd.Parse (argc, argv) should set seed to 1.

Build Date & Hardware: 
ns-3.28 on Mac OS X High Sierra.

Additional Information: 
none.