Release v0.8.3 — Security update, plus everything from v0.8.2

This release updates bundled components with reported security issues. It also carries all of v0.8.2 below, in case you skipped it.

Thanks to @zkendall and @sunao1222 for their contributions.

Features

Choose editor margins in Settings → Editor: Small, Medium, Large or Pageless, which fills the whole editor area (#169)
Move through the workspace file tree with the keyboard: arrow keys, Home/End, Enter to open, F2 to rename (#170)
See the print preview split into real pages, so you can check page breaks and page numbers before printing (#163)
Install MerMark on NixOS with the included Nix package (#174)

Update bundled components with reported security issues
Fix headers, footers and page numbers missing from printouts on Linux and macOS (#163)
Fix the Paragraph/Headings list in the toolbar doing nothing (#171)
Fix line breaks and paragraphs inside quotes being merged into one line when saving (#173)
Fix auto-save writing an empty file while the code view is open
Fix numbered equations showing (0) and scrollbars around formulas in the PDF preview and printout
Fix dollar amounts in indented code being shown as formulas in files with Windows line endings
Fix a crafted image or link address in a Markdown file adding unwanted behaviour to the page