Solution: switch to Github Actions
Travis recently started enforcing credits for OSS projects without
any funding. While it is possible to get free credits, it is a manual
step that involves contacting customer support via email and asking to
add them, every week. While this does not require money, it requires
something far scarcer: volunteers time.
Drop Travis and migrate to Github Actions.
Solution: Modify the build scripts so the user can specify the platform
for which to build, e.g. `./build.sh arm`. This approach originally
significantly reduces the parameters which have to be set before running
the script.
Further the build process is documented in a README now.
* Clarify used C++-standard for compilation.
* More than a conforming compiler may be necessary to compile the library. Just refer to the list of known "good" platforms below.
