interpret 'plaintext' cells with their new name 'raw'

IPython/frontend/html/notebook/static/js/notebook.js

@@ -1197,6 +1197,11 b' var IPython = (function (IPython) {'
             var new_cell = null;
             for (i=0; i<ncells; i++) {
                 cell_data = new_cells[i];
+                // handle short-lived plaintext name for raw cells
+                if (cell_data.cell_type === 'plaintext'){
+                    cell_data.cell_type = 'raw';
+                }
+                
                 new_cell = this.insert_cell_below(cell_data.cell_type);
                 new_cell.fromJSON(cell_data);
             };

IPython/nbformat/v3/nbbase.py

@@ -114,6 +114,9 b' def new_code_cell(input=None, prompt_number=None, outputs=None,'
 def new_text_cell(cell_type, source=None, rendered=None):
     """Create a new text cell."""
     cell = NotebookNode()
+    # handle short-lived plaintext name for raw cells
+    if cell_type == 'plaintext':
+        cell_type = 'raw'
     if source is not None:
         cell.source = unicode(source)
     if rendered is not None:

IPython/nbformat/v3/nbpy.py

@@ -68,7 +68,7 b' class PyReader(NotebookReader):'
                 state = u'markdowncell'
                 cell_lines = []
                 kwargs = {}
-            elif line.startswith(u'# <rawcell>'):
+            elif line.startswith(u'# <rawcell>') or line.startswith(u'# <plaintextcell>'):
                 cell = self.new_cell(state, cell_lines, **kwargs)
                 if cell is not None:
                     cells.append(cell)