Release 0.1.4

- build: require RtAudio 5.2.0 and use its pkgconfig file
- drop stdout usage
- gui|audio: make deleted methods public (https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rc-delete)
- migrate to c++14
- noncopyable: use updated idiom
- doc: add simplified markdown README
- build: drop tr1 namespace (this was only required for pre-c++11)
- update autotools files
- CI: add .gitlab-ci.yml
- configure: don't default warnings as errors
- gui: don't abbreviate label
- Fix underlinking for make {check,distcheck}
- configure: relax JACK requirement (We only directly depend on jackringbuffer)
- build: fix underlinking of JACK
- MTGui: use glib instead of building config dir by hand
- relax autoconf and gtk requirements
- gui: port to gtkmm3
- tests/audio: use multiple tickers in test
- MTAudio: add reference test