Minor corrections added, documentation updated. Slowly sorting out how the .prj file parameters need to be exported. This will still take some time.

functionality to add the .prj parameters and thinking and what the
user will need to define and what can be added automatically. Added
(dirty prototypical) function to call the generateStructuredMesh.exe given the /bin path.

future, just getting used to workflow again)

added minor corrections to functions after noticing some things in the
benchmark files ("name" attribute of gml points
can also be something else than "origin" now, point tibbles without a
"name" column are now accepted, polylines can now have more than 2
points and are still written to xml correctly)

user_input.R, first one contains S3 methods and second one is a small
test that should be ready to run (if the r2ogs6 package is installed and loaded)