Update LUT routine

[bigfooted]

Proposed Changes

Give a brief overview of your contribution here in a few sentences.
This is a small update of the lookup table routines to prepare for the implementation of the flamelet model. A bug was fixed and the header file definition changed (keywords in sentences are capitalized). Some small textual changes were made.

Related Work

Resolve any issues (bug fix or feature request), note any related PRs, or mention interactions with the work of others, if any.
related to the upcoming PR for feature_new_flamelet

PR Checklist

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• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp), if necessary.

[bigfooted]

@danielmayer I've created a separate PR for the changes that you've made in the existing LUT files. Maybe we can replace these lines with a function:

   if (!line.empty() && (line[line.length()-1] == '\n' || line[line.length()-1] == '\r' )) {
      line.erase(line.length()-1);
    }

[EDIT] I replaced it.

[pcarruscag]

Btw it is usually better to put the doxygen comment on the declaration hpp, but it's fine

[bigfooted]

Thanks, I've moved it to the hpp files. When it goes through the regression tests, I'll merge.