Stability Improvements

Updates to the frequency domain scattering function which allow for chunking, relaxing the upper limit to the size of antennas or antenna arrays which can be considered. This is not as time efficient as transferring the arrays to the GPU and back to the host is not optimised, but does enable larger models, even on computers with a low memory GPU. In addition, a bug in the expected behaviour of the mesh_conversion function has now been fixed, with list detection and conversion, so that if there are multiple triangle meshes in the structure object, it will now convert them to the raycaster format appropriately.