Delete an old dictionary available for selecting the aligment of text.

IPython/nbconvert/preprocessors/revealhelp.py

@@ -47,7 +47,6 b' class RevealHelpPreprocessor(Preprocessor):'
             for index, cell in enumerate(worksheet.cells):
 
                 #Make sure the cell has slideshow metadata.
-                cell.metadata.align_type = cell.get('metadata', {}).get('slideshow', {}).get('align_type', 'Left')
                 cell.metadata.slide_type = cell.get('metadata', {}).get('slideshow', {}).get('slide_type', '-')
 
                 #Get the slide type.  If type is start of subslide or slide,