Modify tlsh_unittest as follows:
- modify -c flag so that its argument can also be a digest value (currently argument is assumed to be a filename).
- add -d <digest> flag so that comparison between 2 digest values can be easily done.
- enhance output of usage function to explain new parameters, including -T and -xlen, and add example usage
- replace 4 space indention with tab indention
Modify test.sh to add new tests for flags -xref and -T.
Add results for the new tests to the expected results directory:
    Testing/exp/example_data.128.1.len.xref.scores_EXP
    Testing/exp/example_data.128.1.xlen.xref.scores_EXP
    Testing/exp/example_data.128.1.len.scores.2.T-201_EXP
    Testing/exp/example_data.128.1.xlen.scores.2.T-201_EXP
Modify output for test 3 in test.sh to include the warning message
Modify results for test 3 in test.sh to include the warning message
    Testing/exp/example_data.128.1.len.scores.2_EXP
    Testing/exp/example_data.128.1.xlen.scores.2_EXP