relax SVN archive

The minimise() method now catches the situation of having no errors of the alignment tensor.

Reverted r4732 as the errors argument is not necessary and already exists as a flag.

The command used was:
svn merge -r4732:4731 .

Wrote errors arg unit test for the align_tensor.init() user function.

This is a new argument to allow the tensor errors to be introduced.

Removed a debugging print statement.

Started to pass data into maths_fns.n_state_model.N_state_opt.

Docstring fix for the linear_constraints() method.

Updated the linear_constraints() method.

The looping over all model parameters is not necessary as constraints only apply to the probs.

Whitespace clean up.

Wrote the param_num() method.

Modified the linear_constraints() method to call param_num() to get the number of params.