Allow formatting in the SUMMARY.md file

[mgeisler]

This first changes mdbook-xgettext so that formatting is preserved from the SUMMARY.md file.

Next, mdbook-gettext is changed to translate text from the SUMMARY.md file without formatting: this is necessary since mdbook strips formatting before sending the TOC to the preprocessor.

Fixes #66.

[mgeisler]

TODO: I would like to add an end-to-end test of this: something which verifies that what we extract in mdbook-xgettext works with what mdbook-gettext expects.

[mgeisler]

TODO: I would like to add an end-to-end test of this: something which verifies that what we extract in mdbook-xgettext works with what mdbook-gettext expects.

I suppose the unit tests here are good enough — and we'll be testing this soon enough in Comprehensive Rust.

[djmitche]

I only took a brief look; hopefully @dyoo can look in more depth?

[mgeisler]

@dyoo, does this look reasonable to you?

[dyoo]

Perhaps ends_with instead of contains?

[mgeisler]

Ah, that would be nice, but we're actually matching against the full list of filenames here: something like src/foo/bar.md:123 src/SUMMARY.md:234.

I could parse this and it would look something like this:

        if !msg
            .source()
            .split_whitespace()
            .filter_map(|source| source.split_once(':'))
            .map(|(path, _)| Path::new(path))
            .any(|path| path.file_name() == Some(OsStr::new("SUMMARY.md")))
        {
            continue;
        }

However, now that I just tried this out, I realize that we cannot make any strong assumptions on where the SUMMARY.md file is: mdbook allows you to configure the source directory.

So the code above is essentially the same as just checking if SUMMARY.md is found anywhere in the string.

[dyoo]

LGTM!