Add <span> tag and limited support for CSS styles to wxHTML.

Parse "style" attributes of the HTML tags and honour those of them that can be
mapped to the HTML 3 attributes.

Also add a handler for <span> tag.

Closes #10631.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64443 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/html/winpars.h

@@ -107,6 +107,8 @@ public:
 
     int GetFontSize() const {return m_FontSize;}
     void SetFontSize(int s);
+    // Try to map a font size in points to the HTML 1-7 font size range.
+    void SetFontPointSize(int pt);
     int GetFontBold() const {return m_FontBold;}
     void SetFontBold(int x) {m_FontBold = x;}
     int GetFontItalic() const {return m_FontItalic;}