[bugfix] Make CreateLine return void instead of INT

There were code paths within CreateLine where the method did return a value,
and others where it didn't.  No caller of CreateLine actually considered
the return values at all.  Hence we may as well decide to not return anything
at all.  This should fix an issue reported by the undefined-behavior sanitizer.

Thanks to Carsten Gräser for pointing this out.
Increase version to 3.11.1