Tests various external fragments with 'use' element:
fill, stroke, text, group, multiple levels, name clash and circular references
SVG fragments defined in an external file are invoked with the 'use' element.
The test is passed if the following objects are rendered:
- Top; square with horizontal gradient fill from orange to yellow, and 3 circles all with a blue to red gradient fill
running diagonally inside the square
- Second; green square with a yellow circle in the middle
- Third; the letters ABC in an SVG font
- Bottom; the English alphabet a to j in the shape of a square
