Options page modernization

[wheelercj]

Currently, Stardown's options page is very simple. I would like to keep it easy to use and lightweight, but there are many ways it could be improved.

For example, the options page could let users directly:

• [ ] report bugs
• [ ] request a feature
• [ ] donate

All without navigating to GitHub or another website.

[wheelercj]

In the future, settings for customizing markdown formatting will probably be added, such as:

• code block style: fenced or indented. If fenced, backticks or tildes.
• heading style: atx or setext
• bold style: ** or __
• italic style: * or _
• indent with 4 spaces or a \t
• inline links or reference links
• whether to convert superscripts like y^[1] to y[1] or y^[1]^, and subscripts like H₂O to H2O or H~2~O (the latter of each use the rarely supported markdown syntax explained in Extended Syntax | Markdown Guide)
• whether to align tables

[wheelercj]

@chizuo about grouping the settings that Stardown currently has, here's what I'm thinking:

• General
  • Output markup language: ___
  • Copying links for all tabs copies from tabs in ___
  • Include a text fragment when creating a link for a selection (sometimes impacts performance)
  • Show warning notifications (warnings indicate partial success)
  • Show success notifications
• Readability
  • Omit navigation elements from source format selections
  • Omit footer elements from source format selections
  • Omit hidden elements from source format selections
• Markdown
  • When creating markdown of a selection, ___
  • Markdown bullet point symbol: ___
  • Replace square brackets in markdown link text with ___
  • Optimize markdown of YouTube videos for ___
• JSON
  • Empty table cells are converted to ___ in JSON
  • Save JSON output to ___