somme support for utf-8 in latex

This allow the use of some utf-8/unicode in the ipynb->latex conversion.

tested in codecell comment and markdown.

Most of the caracter with accent, and thins like squareroot symbol and
so on find their way through until the .tex file, but pdlatex
compilation only works out of the box only with accentuated letters

nbconvert.py

@@ -80,11 +80,11 b' def markdown2latex(src):'
     """
     p = subprocess.Popen('pandoc -f markdown -t latex'.split(),
                          stdin=subprocess.PIPE, stdout=subprocess.PIPE)
-    out, err = p.communicate(src)
+    out, err = p.communicate(src.encode('utf-8'))
     if err:
         print(err, file=sys.stderr)
     #print('*'*20+'\n', out, '\n'+'*'*20)  # dbg
-    return out
+    return unicode(out,'utf-8')
 
 
 def rst_directive(directive, text=''):
@@ -139,9 +139,9 b' class Converter(object):'
                 if cell.cell_type in ('markdown', 'raw'):
                     remove_fake_files_url(cell)
                 lines.extend(conv_fn(cell))
-                lines.append('')
+                lines.append(u'')
         lines.extend(self.optional_footer())
-        return '\n'.join(lines)
+        return u'\n'.join(lines)
 
     def render(self):
         "read, convert, and save self.infile"
@@ -481,12 +481,12 b' class ConverterLaTeX(Converter):'
           Name of the environment to bracket with begin/end.
 
         lines: """
-        out = [r'\begin{%s}' % environment]
+        out = [ur'\begin{%s}' % environment]
         if isinstance(lines, basestring):
             out.append(lines)
         else:  # list
             out.extend(lines)
-        out.append(r'\end{%s}' % environment)
+        out.append(ur'\end{%s}' % environment)
         return out
 
     def convert(self):
@@ -539,7 +539,7 b' class ConverterLaTeX(Converter):'
             return []
 
         # Cell codes first carry input code, we use lstlisting for that
-        lines = [r'\begin{codecell}']
+        lines = [ur'\begin{codecell}']
         
         lines.extend(self.in_env('codeinput',
                               self.in_env('lstlisting', cell.input)))
@@ -553,7 +553,7 b' class ConverterLaTeX(Converter):'
         if outlines:
             lines.extend(self.in_env('codeoutput', outlines))
 
-        lines.append(r'\end{codecell}')
+        lines.append(ur'\end{codecell}')
 
         return lines
 

preamble.tex

@@ -5,6 +5,8 b''
 \usepackage{amsmath}
 \usepackage{amssymb}
 \usepackage{graphicx}
+\usepackage{ucs}
+\usepackage[utf8x]{inputenc}
 
 % needed for markdown enumerations to work
 \usepackage{enumerate}
@@ -58,9 +60,11 b''
  {\endMakeFramed}
 
 % Use and configure listings package for nicely formatted code
-\usepackage{listings}
+\usepackage{listingsutf8}
 \lstset{
   language=python,
+  inputencoding=utf8x,
+  extendedchars=\true,
   aboveskip=\smallskipamount,
   belowskip=\smallskipamount,
   %xleftmargin=3mm,