EPUB Output:Replace newlines and all other whitespace in TOC with simple spaces, as Adobe DE cant handle non space whitespace characters in the TOC.

src/calibre/ebooks/metadata/ncx.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0"  encoding="UTF-8"?>
 <?python
 from uuid import uuid4
+import re
 ?>
 <ncx version="2005-1" 
      xml:lang="en" 
@@ -19,7 +20,7 @@ from uuid import uuid4
     <py:def function="navpoint(np, level)">
         ${'%*s'%(4*level,'')}<navPoint id="${str(uuid4())}" playOrder="${str(np.play_order)}">
             ${'%*s'%(4*level,'')}<navLabel>
-                ${'%*s'%(4*level,'')}<text>${np.text}</text>
+                ${'%*s'%(4*level,'')}<text>${re.sub(r'\s+', ' ', np.text)}</text>
             ${'%*s'%(4*level,'')}</navLabel>
             ${'%*s'%(4*level,'')}<content src="${unicode(np.href)+(('#' + unicode(np.fragment)) if np.fragment else '')}" />
             <py:for each="np2 in np">${navpoint(np2, level+1)}</py:for>
@@ -28,4 +29,4 @@ from uuid import uuid4
     <navMap>
     <py:for each="np in toc">${navpoint(np, 0)}</py:for>
     </navMap>
-</ncx>
+</ncx>