Minor 1.5 (#18)

- Updated repository documentation: added contribution guidelines, Code of Conduct, GitHub templates
- Updated README
- Added confirmation dialog for tabs and collections deletion (#17)
- Complete code refactoring (HTML/JS/CSS)
- Implemented <iframe> base for embedded pane (#13) (Fixed CSS instability on some websites)
- Improved dark theme
- Added opensource fonts to replace Segoe UI on Unix systems (#11, #17)
- Fixed invisible vertical scrollbar
- Code polish and improvement

Co-authored-by: Amine A. <15179425+AmineI@users.noreply.github.com>
Co-Authored-By: Michael Gordeev <michael@xfox111.net>

icons/arrowRight.svg

@@ -0,0 +1,5 @@
+<!-- Exported by Character Map UWP -->
+<svg height="100%" viewBox="0 42 1021 941" width="100%" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+  <path d="M1021,512L550.5,982.5L505.5,937.5L899,544L0,544L0,480L899,480L505.5,86.5L550.5,41.5Z" fill="#000000" fill-opacity="1">
+  </path>
+</svg>