Created the N_state_model.test_CaM_IQ_tensor_fit system test.
This is for catching bug #22849 (https://gna.org/bugs/?22849), the failure of the N-state model
analysis when optimising only alignment tensors using RDCs and/or PCSs.
This new test checks code paths unchecked in the rest of the test suite, and is therefore of high
value.