... and in the process, deeply rewrite the text extraction code to be
more flexible with regards to reading/writing non top-to-bottom,
left-to-right text.
Major kudos and thanks to @afriedman412 for the initial idea, initial
prototype, and inspiration for these new features.
Breaking change: word["direction"] is no longer {1,-1} but instead
{"ltr","rtl","ttb","btt"}.
Deprecated: Text-extraction parameters `horizontal_ltr` and
`vertical_ttb`.
Jeremy Singer-Vine