Add comma as a splitting token in toTitleCase()

[Bisaloo]

tools::toTitleCase() documentation indicates that words surrounded by single quotes are protected from change:

However, unknown technical terms will be capitalized unless they are single words enclosed in single quotes: names of packages and libraries should be quoted in titles.

But this doesn't work when the quoted word is immediately followed by a comma:

tools::toTitleCase("Import and Export 'SPSS', 'Stata' and 'SAS' Files")
#> [1] "Import and Export 'Spss', 'Stata' and 'SAS' Files"

tools::toTitleCase("Import and Export 'SPSS' 'Stata' and 'SAS' Files")
#> [1] "Import and Export 'SPSS' 'Stata' and 'SAS' Files"

^{Created on 2024-07-12 with reprex v2.1.1}

The proposed patch fixes this by adding the comma to the splitting tokens.

I have verified on my local library on 1400 R packages that this does not cause any unexpected changes when applied to their Title field in DESCRIPTION.

This is the result of a collaboration with @sarahzeller @shannonpileggi @reikookamoto at the R Dev Day PLUS 2024.

Once checks have been confirmed passing, I will submit this report & patch proposal as a new bugzilla entry.

[Bisaloo]

Submitted bug report & proposed patch in https://bugs.r-project.org/show_bug.cgi?id=18764.