SPRINT: Refactor parts of the codebase

[ljvmiranda921]

Description

A large pull request that deals mainly with refactoring some parts of the codebase. Specifically:

• The tests for topology and high-level optimizers
• Error-handling from LBYL to EAFP
• Remove if-else hierarchy in General Optimizer

Related Issues

#232, #240, #241

Motivation and Context

It is important that we make our code scalable, and has a consistent design before we add bigger features.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[ljvmiranda921]

Refactor GeneralOptimizer

Abstract compute_gbest into one API call

The idea is to change compute_gbest(self, swarm) into something like compute_gbest(self, swarm, **kwargs) so that all other params such as p, k, and r can be relegated locally to the topologies.
From this, you can just use one API call when calling compute_gbest here: https://github.com/ljvmiranda921/pyswarms/blob/development/pyswarms/single/general_optimizer.py#L260

Delegate error handling in __init__ to the actual topologies

Goal is to remove all error-handling in Generaloptimizer. Have the individual topologies handle that:

• Case for Ring: https://github.com/ljvmiranda921/pyswarms/blob/development/pyswarms/single/general_optimizer.py#L171
• Case for Random, VonNeumann and Ring: https://github.com/ljvmiranda921/pyswarms/blob/development/pyswarms/single/general_optimizer.py#L184