RichElementImage - Add support for scaling

[theunwisewolf]

THIS PROJECT IS IN DEVELOPMENT MODE. Any pull requests should merge to branch dev, otherwise will be rejected immediately.

Describe your changes

Added support for "scaleX", "scaleY" and "scale" tags for rich text tag. Added support for width/height in percentage. E.g. <img width="150%" /> Also fixed a bug with the url attribute. Even if you didn't put a url in your img, it will still call openUrl() for some reason.

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [x] If it is a core feature, I have added thorough tests.

[halx99]

What about implement html standard width="150%"

[theunwisewolf]

Check @halx99