DOC: Hyperlinks to QuTiP functions and classes

It would be nice if the docstrings in QuTiP were well formatted, such that, when Sphinx builds the API and guidelines documentation, there are working link to QuTiP functions and classes. An example of working link is qutip.steadystate.steadystate in http://qutip.org/docs/latest/guide/guide-steady.html#steady-state-solvers-in-qutip

An example of working link in the API doc is options: qutip.solver.Options in the attributes of the HEOMSolver class http://qutip.org/docs/latest/apidoc/classes.html#non-markovian-solvers

A way to proceed would be to:

1. reformat all instances in the docstrings of qutip/qutip such that they are in the form of :py:meth:mymodule.MyClass.mymethod, see https://stackoverflow.com/questions/22700606/how-would-i-cross-reference-a-function-generated-by-autodoc-in-sphinx

2. Build the documentation with Sphinx to check that the change works and generates an active hyperlink in the relative html page of the documentation.

3. Iterate 1) and 2) for instances in which Qobj or other QuTiP functions or classes are found.

[spinolino]

I just registered for the unitaryhack and saw this issue. I could have a look at it.

[nathanshammah]

An example is in the Dicke class of PIQS, the permutational invariant solver. The docstring says

Parameters: | N: int
The number of two-level systems.
hamiltonian: :class: qutip.Qobj
A Hamiltonian in the Dicke basis.The matrix dimensions are (nds, nds), with nds being the number of Dicke states. The Hamiltonian can be built with the operators given by the jspin functions.

Ideally, the hamiltonian specification as :class: qutip.Qobj should be a hyperlink. Formatting it correctly with :: and the correct spaces should make it work.

Another example is in the docstring of the basis(), and bell_state() functiona, which returns a state:qobj. This could point to the Qobj class.