Add cleanup action for "LaTeX to LaTeX aware Unicode"

[JasonGross]

Problem:

• There is no cleanup action that allows converting (old) bibliographic data that is (still) formatted in LaTeX with Non-Unicode characters to Unicode aware LaTeX formatting (newer LaTeX engines (e.g. LaTeX2e) can now read most Unicode characters).
• Current workarounds include converting to from LaTeX to Unicode and then back to LaTeX, while manually checking, if any characters were wrongly converted. This is inefficient and takes a long time.
  • This workaround is bothersome, because there are symbols that do not get converted when using LaTeXToUnicode and UnicodeToLaTeX cleanup actions (e.g. #3644) and there are other special symbols that SHOULD not get converted automatically, because multiple conversions are possible and users would need to take take manually (e.g. #8712)

Desired Solution:

• Create cleanup action for "LaTeX to Unicode aware LaTeX".

Example workflow:

1. Have the following entry (BEFORE using the cleanup action):

     @Article{Testkey,
       author   = {Testauthor},
       title    = {Bibliographic data that can be read by LaTeX engines},
       a = {Here is a backslashed percentage sign \% and it should be excluded from conversion},
       b = {Here is a \textcopyright{} and it should be converted to Unicode}, 
     }

   (Comment: \textcopyright{} can be converted to © by the inputenc package. When using the LaTeX to Unicode aware LaTeX cleanup action, the result of the conversion should also be ©)

2. Use cleanup action "LaTeX to Unicode aware LaTeX"

3. AFTER using the cleanup action, the following result should emerge:

     @Article{Testkey,
       author   = {Testauthor},
       title    = {Bibliographic data that can be read by LaTeX engines},
       a = {Here is a backslashed percentage sign \% and it should be excluded from conversion},
       b = {Here is a © and it should be converted to Unicode}, 
     }

"Special Symbols" that would need to be excluded from conversion:

• The list should be similar to the symbols mentioned in #8712.
• At the very least Page 15 (Tables 1); Table 1 lists escapable special characters in LaTeX.
• Maybe also Page 15 Table 2 and Page 16 Table 3.
• There might be a lot more, but I am not knowledgable enough to list them here. If you know of any, just post it in this thread.

Additional Information

• When working on this, The Comprehensive LATEX Symbol List will be of help. Especially chapters about "Unicode" (Page 272) and "Special Characters" (Page 15-16).
• JabRef currently uses https://github.com/tomtung/latex2unicode; Maybe it can be adapted internally in JabRef (e.g. some pre-processing). Another solution would be to fork it or ask tomtung about creating a LaTeX2UnicodeAwareLaTeX converter.

Originally posted by @ThiloteE in https://github.com/JabRef/jabref/issues/8490#issuecomment-1107461770

[zkl-ai]

Hello, can I take this issue? I have done something related to cleanup actions.

[ThiloteE]

Sure you can!