2.6.0

Changes:

• Added support for opening HTML files (#641)
• Consistent inner and outer margins (#255)
• The automatic layout no longer supports 4 columns (58d5e50)
• Fixed long words overflowing (#654)
• Fixed custom themes not saved across sessions (#660)
• Fixed shortcuts for key pads (#677)
• Fixed opening non-UTF-8 zipped FB2 files (#629)
• Fixed books not opening on GNOME 40 (#689)