Merge WB develop branch and fix behat tests

[dasistwas]

I have done some modification in travis.yml. Behat now breaks. Could you merge the branch and try to fix the behat tests?

[michaelpollak]

PHP7.2 seems to fail because of errors in the moodle ci build matrix, out of our control as far as I was able to determine. I created a test array that currently stays with PHP7.1 but to test mdl3.9 we have to find a solution that works with >= PHP 7.2

MDL3.6 also fails but that is known for a while.

MDL3.8 is throwning errors that were not there last time I ran the tests, will look into this.

[dasistwas]

OK, let's focus on the tests where behat actually runs:
https://travis-ci.org/github/Wunderbyte-GmbH/moodle-mod_datalynx/jobs/698603920

For Moodle 35 I think we can not test with PHP7.1 so maybe we replace the test with php7.2 and M35

[dasistwas]

PHP 7.4 works with M3.8 and M3.9

[michaelpollak]

Travis just is no fun.
So our tests work, I went back to the trusty VM because on bionic somehow 3.7 and 3.8 failed.
3.5 works with PHP7.1 even under bionic. Will test some more, it's mainly pushing and a lot of waiting...

https://travis-ci.org/github/michaelpollak/moodle-mod_datalynx