ghostwriter++ 2.1.6-2

Preview Editing:
- Completely re-write preview editing system. Diff-based apply that only touches source ranges belonging to TEXT AST nodes inside the edited element, rejecting edits that would break formatting.

Small changes/fixes:
- Add "Open in browser" right click context menu option for links bc left-clicking now edits it
- Fix issue that would cause changes fail to update on view/focus change until app restart

Implement every possible .md formatting option systematically:

Done:
- general text
- headers (ATX + Setext)
- links (in-line preview edit only currently supports editing user-facing text)
Inline:
- GFM strikethrough
- Strong
- Emphasis
- Code spans
- Bullet / ordered lists
- Nested lists
- Task lists