Main trunk of the basic code finished

Now the basic trunk of the code has been finished. But prior to the
major debugging and testing, a major clean-up is needed, especially in
the hilbert.py module. Now this module contains HilbertSpace,
SingleParticleSpace and FockSpace separately in a complicated code for
no good reason. This is just a result of the prior influence of the
sympy.physics.quantum package. Now it needs to be changed.