Fix bug involving weird sort order of nested tables

Also, tidies up the containers special case, handling in one place
and simplifying the type interface to only be Item

Fix Container Bug

An edge case involving AoT's returns a Container, not an Item, while recursing. This PR re-adds the Union[Item, Container] handling and adds a test for the case.

It also improves the README.

Option to not print header

Add command line option to not print a document's leading comments.

Also, simplifies / shortens the help message (it was too long before)

Standardize cli help strings

v0.12.1

Bump version

Preserve top-level comments

Comments at the beginning of the TOML document are preserved. These are considered the document "header" and are not associated the ordered elements. Comments throughout the document cannot be consistently ordered.

I may add a command line option to enable / disable this in the future. It's a simple feature toggle.

Performance enhancements

Stops creating unnecessary lists for each recursive element; just returns an iterable now

Simplify help message when no arguments passed

Previous behavior was broken, now it works simply without trying to print out full message

Replace --ignore-non-tables with --all

 Make not sorting non-table keys the default with --all

 Replaces the --ignore-non-tables option with the --all option (its
 opposite).

Fix indentation, remove option for super tables

Indentation now standardized, super tables option unnecessary

Fix AOT Parsing, option for Super Tables!

• Parses AoT's correctly
• Adds option to include Super Table headers, for those who want them