Library refactor and multiple bugfixes

[dancol90]

This PR collects many long-due refactors and fixes and make it work with newer Arduino core versions.

List of changes:

• Codestyle refactor
• Move implementation to C++ file
• Replace esp_yield() with delay() and custom logic to wait for completion

List of affected issues and PR:

• Replaces #27
• Replaces #36
• Replaces #42
• Fixes #35
• Fixes #37
• Fixes #40
• Fixes #41
• Fixes #44

[dancol90]

Thanks to @d-a-v, @majenkotech and @jeroenst for the contributions.