Getting ready for 1.2.0 release: many smaller requests implemented

- Implements #7
- Implements #42 and therefore #64
- Improved #53
- Implements #59
- Implements #61
- Implements #63
- Implements #80
- Implements #84
- Added Info page
- Removed Help page
- Bumped version number to 1.2.0
- Fixed a bug where wide mode was still 720px wide
- Created FUNDING.yml
- Reorganised arguments in README.MD and documented new options
- Updated SECURITY.MD
- Added display of last read time and read count
- Increased default width to 800px to make UI less cluttered
- Reorganised index page
- New, better attach file button

I want to spend some time testing these changes and let everyone have a look at them before tagging and releasing new artifacts.

templates/qr.html

@@ -0,0 +1,7 @@
+{% include "header.html" %}
+
+<div style="text-align: center">
+  {{qr}}
+</div>
+
+{% include "footer.html" %}