The existing targets for precise and osx breaks, both on dependencies.
Seems to be about the 'rosdep install' command in the Makefile(?),
which is beyond my current scope.
Add a new target for Ubuntu focal which works after refactoring the
.travis.yml file.
Gbp-Pq: Name 0011-ci-.travis.yml-Refactor-add-working-focal-build.patch
travis
Although this patch better matches the state before the re-factoring, it
doesn't mean that much since the build breaks already in the install
stage.
While on it, fix some yamllint nitpicks.
* reduce the number of jobs on travis
* update usage of pip due to changes in Homebrew
* update pip and ensure the right one is being used with an alias
* force reinstall pip to get `pip` on PATH
* use python2 explicitly to run catkin_make
* force use of python2 executable by catkin packages
* python!
* simpler
* how to which
* Update .travis.yml
* make tests and run_tests
* test results
* disable timer tests on macOS
