Made default font size so when user doesn't enter a font size it doesn't cause an error.
Added ellipse.
Added optional transparent background
Removed Shavian fonts because they didn't work with CSS and they were missing the
letters (𐑥, 𐑯 𐑢 and 𐑼) when used Imagemagick so they of limited use.
Every alternative I could find either displayed regular text or nothing at all.
Added urlencode() to text input for image URL to fix bug when '#' character inputed.