docstring for option validator
memcpyMat now only allows transposed matches if it's (n x 1) and (1 x n), not (m x n) and (n x m)
refactor RtIntegrator to use RtIntegratorOptions in a safe way, and generate custom export_integrator.cpp instead of a generic one
minor ocprt cleanup, stuff found when showing milan through the code
only do the RtIntegrator ctypes.loadlibrary and lib.export_integrator in a subprocess so that we get nicer error messages
refactor ocp export options to use Options classes, separating integrator and codegen options