bump_crengine: various fixes, tweaks and cleanups (#6188)

Includes:
- Don't reset invisible BR to display: inline
- ldomTextCollector: handle inline-block/table as inline
- Avoid re-rendering on font hinting mode change
- List markers: fix positionning when floats involved
- GIF decoding: avoid uneeded abort on LZW table overflow
- Adds getUnknownEntities(), can help with debugging
- Don't check stylesheet hashes when loading from cache
- Hardcoded elements and attributes list: cleanup
- Full rendering: 2 small optimisations
- Strut confinning: deal with images earlier
- lvtextfm: some cleanup and reordering
cre.cpp:
- fix getPageFromXPointer() and getPosFromXPointer()
  to not fail on invisible nodes and work on the next
  visible node (so links whose target is display:none
  can work).

Add support for 2 settings one can set manually
in reader.settings.reader.lua:
["cre_background_color"] = "0xccffcc",
["cre_background_image"] = "/path/to/bg_paper.jpg",

frontend/apps/reader/modules/readerrolling.lua

@@ -258,6 +258,11 @@ function ReaderRolling:onCloseDocument()
         end
     end
     logger.dbg("cre cache used:", cache_file_path or "none")
+    -- Unknown elements and attributes, uncomment if needed for debugging:
+    -- local elements, attributes, namespaces = self.ui.document:getUnknownEntities()
+    -- if elements ~= "" then logger.info("cre unknown elements: ", elements) end
+    -- if attributes ~= "" then logger.info("cre unknown attributes: ", attributes) end
+    -- if namespaces ~= "" then logger.info("cre unknown namespaces: ", namespaces) end
 end
 
 function ReaderRolling:onCheckDomStyleCoherence()