Adds "Better rendering of list items" to Style tweaks (#3968)

Alternate rendering of list items as block elements (instead of
inline/final).
Check the built DOM is still coherent with styles on stylesheet
change, and propose to reload the document if not. Also
invalidate cache on close in that case so a new DOM is built
at next opening.
ReaderStyleTweak: fix tweak css duplication; when globally
enabled, when disabling and re-enabling locally, the css would
be added twice to the final CSS.
Also adds !important to "sub_sup_smaller" tweak, and increase
its priority so it can override "font_size_all_inherit".
Adds CreDocument:getCacheFilePath() for futur features.

frontend/apps/reader/readerui.lua

@@ -650,4 +650,17 @@ function ReaderUI:onHome()
     return true
 end
 
+function ReaderUI:reloadDocument(after_close_callback)
+    local file = self.document.file
+    local provider = getmetatable(self.document).__index
+    self:handleEvent(Event:new("CloseReaderMenu"))
+    self:handleEvent(Event:new("CloseConfigMenu"))
+    self:onClose()
+    if after_close_callback then
+        -- allow caller to do stuff between close an re-open
+        after_close_callback(file, provider)
+    end
+    self:showReader(file, provider)
+end
+
 return ReaderUI