Readabs

- Minor changes
* largely tidy-ups.

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- Major changes
* removed the old-docs directory.
* Finished documenting the API, using pdoc3

- Minor changes
* Some code reorganisation

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- Major changes
* Removed the incomplete documentation from the
'README.md' file.
* Worked out the proper import arrangements. Removed the
'readabs.py' file. Expanded '__init__.py'
* Removed the generate_catalogue_map.py and rewrote the
abs_catalogue.py to dunamically download the catalogue.
* Started using pdoc3 to automate the generation of API
documents. API comments are a work in progress, and
there is no guarantee I will stick with pdoc3.

- Minor changes
* Added __all__ to __init__.py, to allow for wildcard
imports
* Applied mypy and pylint to the package. Down to zero
mypy issues and one pylint issue.
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- Major changes
* put the recalibrate() function into its own module.
Added some in-module tests.
* Removed the ./tests directory. In the interim, I have
been placeing quick code-tests inline. Will need to
more sensibly revisit code testing in the future.
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- Minor changes
* Further code tidy-ups
* tidy-ups to read_rba_ocr() in read_rba_table.py
* removed a print statment from get_rba_links.py
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- Major changes
* Completed initial work to read in data files from the
Reserve Bank of Australia (RBA). This will need work
over the next few days.
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