Overview:
The compiler treats uint8_t as char for printing. For uint8_t this not only does not make sense, but also causes a crash of test.py when it is supposed to generate an HTML report, as it cannot handle control characters.

Steps to Reproduce: 
1) Create a test suite / case that compares two uint8_t's. Example:
      uint8_t a = 3;
      uint8_t b = 5;
      NS_TEST_ASSERT_MSG_EQ (a, b, "This should fail.");
2) Run test.py for the newly created test-suite with the option to create an HTML report.


Actual Results: 
test.py crashes in  translate_to_html.

Expected Results: 
The test framework should detect the uint8_t and treat it as a number. A report should be created as usual.

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

Additional Information: 
The reason for this is that uint8_t gets treated as a char when printing. std::to_string can solve this. However, simply adding std::to_string to the macro would not work since std::to_string does not accept strings as input. Maybe the NS_TEST_ASSERT_MSG_EQ and other macros can be replaced by function templates? Alternatively, this could be fixed by writing the actual number to the results.xml instead of treating uint8_t as a character there. 

As a workaround, the user can cast every uint8_t he gives to the macros to uint16_t. Even if this issue will not be fixed, the need of casting uint8_t variables should be documented.