bump crengine: better SVG support with extended LunaSVG

Build crengine against LunaSVG instead of NanoSVG.
Includes:
- SerialBuf: allow serializing longer strings
- Support '<img src="data:image/svg+xml,<svg...', remove ;-cr-plain,
- CSS: attribute selectors: accept ' or " as the quote char
- Embedded fonts: fix ignored name when sharing same url
- LVImg: fix possible crash on GIF images
- Fonts: DrawTextString(): allow collecting glyphs as SVG paths
- Images parsing: cache native sizes
- SVG: enhanced SVG support with LunaSVG extended
- Add ldomNode::isImage(), handle <object> and <embed> as images
- Handle the <svg> element as an SVG image
- Support SVG images as first class documents

Make credocument the preferred engine for .svg files.

frontend/document/pdfdocument.lua

@@ -389,7 +389,7 @@ function PdfDocument:register(registry)
     registry:addProvider("png", "image/png", self, 90)
     registry:addProvider("pnm", "image/x‑portable‑bitmap", self, 90)
     registry:addProvider("ppm", "image/x‑portable‑bitmap", self, 90)
-    registry:addProvider("svg", "image/svg+xml", self, 90)
+    registry:addProvider("svg", "image/svg+xml", self, 80)
     registry:addProvider("tif", "image/tiff", self, 90)
     registry:addProvider("tiff", "image/tiff", self, 90)
     -- Windows Media Photo == JPEG XR