v4.1.8

• Fixed Sankaku Channel source.
• Fixed Gelbooru source.
• Fixed source addition and Gelbooru 0.1.11 (issue #281).
• Fixed division by zero errors on error pages (issue #387).
• Fixed single downloads not being properly deleted (issue #436).
• Fixed multiple login tries and add login settings for Gelbooru.
• Fixed background staying white even on high contrast black (issue #432).
• Fixed details and zoom window sometimes using wrong extension (issue #425).
• Improve loading speed when restoring a lot of single downloads.