Unstructured

* Added the ability to pull an HTML document from a url in `partition_html`.
* Added the the ability to get file summary info from lists of filenames and lists
of file contents.
* Added optional page break to `partition` for `.pptx`, `.pdf`, images, and `.html` files.
* Added `to_dict` method to document elements.
* Include more unicode quotes in `replace_unicode_quotes`.

* Loosen the default cap threshold to `0.5`.
* Add a `UNSTRUCTURED_NARRATIVE_TEXT_CAP_THRESHOLD` environment variable for controlling
the cap ratio threshold.
* Unknown text elements are identified as `Text` for HTML and plain text documents.
* `Body Text` styles no longer default to `NarrativeText` for Word documents. The style information
is insufficient to determine that the text is narrative.
* Upper cased text is lower cased before checking for verbs. This helps avoid some missed verbs.
* Adds an `Address` element for capturing elements that only contain an address.
* Suppress the `UserWarning` when detectron is called.
* Checks that titles and narrative test have at least one English word.
* Checks that titles and narrative text are at least 50% alpha characters.
* Restricts titles to a maximum word length. Adds a `UNSTRUCTURED_TITLE_MAX_WORD_LENGTH`
environment variable for controlling the max number of words in a title.
* Updated `partition_pptx` to order the elements on the page

* Updated `partition_pdf` and `partition_image` to return `unstructured` `Element` objects
* Fixed the healthcheck url path when partitioning images and PDFs via API
* Adds an optional `coordinates` attribute to document objects
* Adds `FigureCaption` and `CheckBox` document elements
* Added ability to split lists detected in `LayoutElement` objects
* Adds `partition_pptx` for partitioning PowerPoint documents
* LayoutParser models now download from HugginfaceHub instead of DropBox
* Fixed file type detection for XML and HTML files on Amazone Linux

* Adds `requests` as a base dependency
* Fix in `exceeds_cap_ratio` so the function doesn't break with empty text
* Fix bug in `_parse_received_data`.
* Update `detect_filetype` to properly handle `.doc`, `.xls`, and `.ppt`.

* Added `partition_image` to process documents in an image format.
* Fixed utf-8 encoding error in `partition_email` with attachments for `text/html`

* Added support for text files in the `partition` function
* Pinned `opencv-python` for easier installation on Linux