HTML to TEXT/MARKDOWN cleanup and refactoring

[caronc]

Description:

Related issue (if applicable): #527

@YoRyan , maybe you could have a look at this branch and check out the last test i wrote that isn't passing.

I had to re-factor your work a little to cover more cases; but you still had a fantastic start.

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• No lint errors (use flake8)
• 100% test coverage

[YoRyan]

If we restrict ourselves to the primitive parser in the standard library, some limitations are inevitable—web browsers specialize in parsing this kind of badly formatted HTML, after all. Nevertheless, after giving the code my own rework, I have gotten it to pass all of your tests. 🙂

fix-html-converter.patch

[codecov-commenter]

Codecov Report

Merging #530 (5bb6e5c) into master (8fa1466) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #530   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          106       106           
  Lines        13565     13597   +32     
  Branches      2501      2511   +10     
=========================================
+ Hits         13565     13597   +32     

Impacted Files	Coverage Δ
apprise/Apprise.py	100.00% <100.00%> (ø)
apprise/conversion.py	100.00% <100.00%> (ø)

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[caronc]

@YoRyan ; I think we nailed it between both of our changes. I couldn't have done it without you! I'll merge this and work on an official release next. 🚀