GitLab

Created by: IIaKyJIuH

Added preprocessors cacher class:

• Created base cacher class for pipelines and preprocessors items.
• Refactored DataPreprocessor class and added its items cacher using sqlite3 database.
• Moved main API caching options to the composer's
• Moved pipelines_caching.py example to the separate repository
• Minor: rid of deprecated .warn logger messages; fixed singleton log initialization by wrapping some of the class fields into the property decorator; semantized docstrings; fixed caching via multiprocessing in data_objective_builder.py; code style/type fixes