Moving towards weblate #3: Tutorial transition

[hzulla]

This makes the tutorial translation possible through Weblate.

The existing translated Markdown versions have been removed and imported to .po files, which is the format used by Weblate (and similar translation workflow services). I have tried to import the existing (partially incomplete) translations as faithfully as possible, but it still requires a proofreading afterwards. That proofreading only needs to be done once.

The English Markdown files have been moved back into doc/etc/tutorial.

The i18n-tool.rb script is used to generate the translated versions in doc/etc/generated/<lang>/tutorial/ during build.

The i18n-tool.rb script also creates the .pot translation template file from the English markdown, which is later used to merge the updated English tutorial texts with the existing translations. The language file update process is described as usually in TRANSLATION-WORKFLOW.md. rmsgmerge will complain about fuzzy (= guessed) translations during the merge, this is normal and intended behaviour.

The developer experience to build Sonic Pi with this is currently still sub-par, as i18n-tool.rb adds another step to the build process and its source pretty hackish with some hardcoded file locations.

I promise to clean this up, as @Factoid and I want to work on the build scripts together after this. But I wanted to get the tutorial into weblate quickly for the awesome and impatient translators. :-D

If you agree and merge this, I can then ask the Weblate admins to turn on the tutorial translation component on their site.

[hzulla]

A more detailed look into the translation workflow:

• Weblate edits translations in etc/doc/lang/sonic-pi-tutorial-*.po
• i18n-tool.rb -x creates etc/doc/lang/sonic-pi-tutorial.pot from etc/doc/tutorial/*.md
• i18n-tool.rb -u updates the existing .po files with the message strings from the .pot template.
• i18n-tool.rb -t generates translated Markdown files in etc/doc/generated/*

[samaaron]

Incredible work, thanks!