Based on [the version from Salesforce2SQL](https://github.com/acrosman/Salesforce2Sql/pull/32) or [electron-sf-base](https://github.com/acrosman/electron-sf-base/commit/8ba327fab7e1acc246fe4682de28aefbe78feb97), add a basic preferences system that starts with just a theme switcher.
Based on the version from Salesforce2SQL or electron-sf-base, add a basic preferences system that starts with just a theme switcher.