Pre-refactor release

This is the final release to use the old global-oriented codepaths. These will remain in the next release as deprecated code in a separate file, but will be removed in the release after that. There are also numerous other improvements in addition to the work that has prepared this major refactoring, not limited to:

• A basic testing framework and an initial set of tests (thanks to @yrammos)
• Better separation of style from code by using CSS classes and parameters instead of direct inline changes to the style
• Code separation into multiple files to make the structure easier.
• Giving the option to selectively undo just reductions
• Add relation scrolling by keyboard command in addition to scrollwheel