Add support to thumbnails for SVG
Add support to thumbnails for SVG

Thumbnails from SVG need the Imagik extension. If it's not available, let's simply don't create thumbnails


Former-commit-id: a0e68a4121dd51b72a059095e9b50e099fb94ef3
Former-commit-id: aa19477ab07c921c48905f79c4f6c0bd9700b6dc
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