v0.21.0

• Add: Export current level as ZIP With Options.
• Add: Seed in Demo Edit dialog.
• Add: Transpose selection editor.
• Add: Ctrl+A hotkey to select whole level body and Ctrl+Shift+A to select almost whole without border.
• Add: Selection Editors now can work with entire level body without selection.
  • A new Transpose editor can autoresize level when necessary, if underlying format support wanted size.
• Fix: Hovered cell display didn't use Selection own Content.
• Fix: Cannot paste a level with demo signature from clipboard to DAT file.
• Enh: Use level title in filename when exporting a level.

Desktop

• On Linux now libwebkit 4.1 is required (libwebkit2gtk-4.1-0).
• Fix: Several issues potentially causing losing config and/or opened
  files/levels state due to bad and/or unstable concurrent I/O.