Area4

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+ Added API Refrence documentation page
+ Updated tests to work with new Python version
* Changed copyright header
+ Updated Sphinx version

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+ Added 14 new dividers

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+ Added 9 new dividers
+ Made area4.utils.get_raw_file() cache the file contents
* Fixed certain dividers confusing GitHub
+ Added more splitter tests
+ Added test for area4.utils.markdown_horizontal() function
+ Added partially working duplicate divider checking
(disabled due to failures that would be breaking changes)

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+ Added markdown horizontal divider
- Removed rdillib dependency
* Updated docs

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* Updated documentation
* Updated CI to use slim images
- Removed SafetyCI checks, description validation, and old Markdown check
- Removed area4.util_module and area4.theArray aliases
* Renamed area4.author to area4.__author__
+ Added 'text' keyword
- Removed pipenv dependency

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- Removed util.check function
* Fixed dead links
+ Added integer check