[Refactor] Create a uniform constructor for all connectivity structures

[T0nyX1ang]

All the connectivity structures contain three parts:

• initialization (required): define the initial points,
• propagation (required): propagate the full connectivity map with the initial points and a propagation rule (such as an adjacent rule),
• constraint (optional): reachable on a certain area, region, etc.

Hence, it is possible to create a uniform constructor.

The following things are regarded as a connectivity structure:

• [x] reachable, without a known origin (named as reachable/2 in the codes)
• [x] reachable, with some known origins (named as region/2 in the codes)
• [x] reachable to edges (named as reachable_edge/2 in the codes)
• [x] lit, propagate adjacency as a bulb (named as lit/2 in the codes)
• [x] reachable in an area (named as reachable/3 in the codes)
• [x] reachable components (named as reachable/4 in the codes)

[T0nyX1ang]

The former structure is hard to understand, so we are going to remake it. The remake will be more intuitive and understandable, which will try to set the connectivity into three parts:

• initialization
• propagation
• constraint

The final call will become connectivity(initial='init_params', propagation='prop_params', constraint='con_params'), and a rule will be generated eventually.

[T0nyX1ang]

The refactor is almost completed now (in the dev branch).