Small tweaks and new translations

Changes:

• The editor will now not allow you to set positive descent as having descent rise above baseline confuses software in new and unexpected ways.
• Baseline now measures until the bottom of the last pixel above the baseline rather than the top (which makes more sense). Existing JSON configurations are converted to new format automatically and nothing is expected to break.

Translations:

• Added a Spanish translation by Makhor.
• Added a Chinese translation by yunzl.
• See the documentation for making your own translations!