Merge pull request #143 from unittest-cpp/v2-prep
      v2.0.0 prep

Closes #96

Merge pull request #111 from unittest-cpp/v1.6.1-prep
      v1.6.1 prep

Update docs, versions for 1.6.0.
      

Prepare v1.5.1 tag
      

Prepare v1.5.0 tag.
      

Tagging v1.4 as previously released on sourceforge.