Commons extension 0.1.5 - prerelease 2

• Ensure calls to Wikimedia includes an User-agent by @Abbe98 in #192
• Fix various cases causing the category-depth input to be inaccessible to the user by @Abbe98 in f7e482a

Under the hood:

• Migrate to CSS variables by @Abbe98 in 263446a
• Initiate I18N using core extension point by @Abbe98 in 2396cb2