fixes isnan/isinf and memory allocation in spline functions
fixes isnan/isinf and memory allocation in spline functions

FFroehlich/AMICI,AMICI-developer/AMICI,AMICI-developer/AMICI,FFroehlich/AMICI,FFroehlich/AMICI,AMICI-developer/AMICI,FFroehlich/AMICI,AMICI-developer/AMICI