Major Refactor of Session Settings Class

[retiutut]

Problem

I am the one who created this class a few years ago, and I see now that the way this class was designed makes it harder to implement new features and options in widgets.

I really like the way the Hardware Settings are saved for each channel using GSON by serializing a whole class. Such a change would have over-arching changes in all widgets, but would be best moving forward.

Expected

In a perfect setting, users can make a new widget and not have to make changes to Session Settings class. Settings and widget configurations should be "automatic" for developers.

This is a large and difficult lift and should be completed with care and consideration for other developers.

Operating System and Version

All OS

GUI Version

5.0.4

Running standalone app

Standalone and Dev

Type of OpenBCI Board

All boards and applicable widgets

Are you using a WiFi Shield?

All boards and applicable widgets

Console Log

Console log messages regarding this class are normal and expected in 5.0.4.

Example of issues that can arise from all of the hard-coding in SessionSettings.pde: #969