MEALPY: a Framework of The State-of-the-art Meta-Heuristic Algorithms in Python

Update Add save and load model functionalities in mealpy.utils.io module. Add object that hold global/current worst solution in history object Add method create_pop_group() in Optimizer class Add method before_initialization() in Optimizer class Refactor initialization() and after_initialization() in Optimizer class Remove before_evolve(), after_evolve(), and levy_flight() in Optimizer class Convert termination_start() and termination_end() to check_termination() in Optimizer class Remove boundary.py in utils Add set_parameters() and get_parameters() in all optimizers Update new Problem class, move problem parameter from Optimizer to solve() function. Fix bug printing same entry multiple times in logger. Fix bug exit() in Optimizer and utils package. Update new Termination class, move termination parameter from Optimizer to solve() function. Add Multitask class that can run multiple optimizers on multiple problems with multiple trials. Refactor all optimizers. Add Tuner class that can help tuning hyper-parameters of optimizer. Add examples how to build new optimizer. Add examples for Multitask and Tuner class. Update documents, examples, test