* Split file structure into multiple parts
* Added `TableStyle` class for storing info about a theme (all the different parts that make up the table)
* Added `PresetStyle` class with pre-made styles to choose from
* Made a list of styles in `/style_list` and a script for generating the list
* Ensure that user-specified column widths are at least as large as cell contents
* Made `header`, `body`, and `footer` positional arguments (can place with no label); all other options must be keyworded.