C-API should allow periodic calculations with any method

[awvwgk]

Is your feature request related to a problem? Please describe.
The API is currently aware of boundary conditions, which requires an API change for every method that gets new boundary conditions.

Describe the solution you'd like
Generally it would be much easier to separate the calculator from the structure information as much as possible and just reject invalid input (e.g. due to missing implementation of the boundary conditions) by returning an error code.

Describe alternatives you've considered
The alternative is go with the current solution and implement redundant bindings for the same methods.

Additional context
This change might will break the complete API compatibility with previous versions.