[Maarten van Gompel]
- fall back when local config dir can not be checked for whatever reason
#97 - extract custom configuration directory if provided, and fall back to that
for includes #96 - needs ticcutils >= 0.35
[Ko van der Sloot] - force use of c++17
- minor code updates
- streamlined Github CI file
- adapted some foliatests to recent libfolia versions
- refactored tests:
- all shell scripts have the .sh extension now
- use folialint or foliadiff to check folia results