Additional glyphicons for music on search and author page

Fix duplicate user and email (now case insensitive)
Output of calibre on stderr is now logged (full traceback in debug-log, otherwise, only errormessage)
Natural sorting for comic reader
Fix for long running tasks

cps/subproc_wrapper.py

@@ -23,7 +23,7 @@ import os
 import subprocess
 
 
-def process_open(command, quotes=(), env=None, sout=subprocess.PIPE):
+def process_open(command, quotes=(), env=None, sout=subprocess.PIPE, serr=subprocess.PIPE):
     # Linux py2.7 encode as list without quotes no empty element for parameters
     # linux py3.x no encode and as list without quotes no empty element for parameters
     # windows py2.7 encode as string with quotes empty element for parameters is okay
@@ -42,4 +42,4 @@ def process_open(command, quotes=(), env=None, sout=subprocess.PIPE):
         else:
             exc_command = [x for x in command]
 
-    return subprocess.Popen(exc_command, shell=False, stdout=sout, universal_newlines=True, env=env)
+    return subprocess.Popen(exc_command, shell=False, stdout=sout, stderr=serr, universal_newlines=True, env=env)