Added support for removing duplicates from LRF TOC

src/libprs500/ebooks/lrf/pylrs/pylrs.py

@@ -657,6 +657,10 @@ class TableOfContents(object):
         if not hasattr(textBlock.parent, 'objId'):
             raise LrsError, "TOC destination must be appended to a container with an objID"
 
+        for tl in self.tocEntries:
+            if tl.label == tocLabel:
+                return
+        
         self.tocEntries.append(TocLabel(tocLabel, textBlock))
         textBlock.tocLabel = tocLabel
  

src/libprs500/ebooks/lrf/txt/demo/demo.txt

@@ -0,0 +1,89 @@
+Demonstration of `txt2lrf`
+==========================
+
+`txt2lrf` provides a convenient way to create LRF files with good formatting. 
+`txt2lrf` recognizes a simple markup language called *markdown*.
+
+The idea is to provide a lightweight markup that can be used to create
+TXT files that can be read by themselves or automatically converted to LRF.
+[{@name=toc}]()
+
+<br /><br />
+
+///Table of Contents///
+
+
+Text formatting
+---------------
+**Bold** and *italic* text is easily specified.
+
+> Blockquotes are also very simple to specify.
+> This is a basic blockquote paragraph. I absolutely
+> love block quotes don't you?
+
+    This is a preformatted code block. No formatting rules are applied to text in this block and it is rendered in a monospaced font.
+
+  
+For details on the text formatting syntax visit 
+
+    http://daringfireball.net/projects/markdown/syntax
+___
+[Table of Contents](#toc)
+
+Lists
+-----
+Both ordered and unordered lists are supported.
+  
+
+### Unordered lists
+
++ What a
++ *nice*
++ list
+
+  
+
+### Ordered lists
+
+1. One
+2. Two
+3. Three
+
+**Note:** Nested lists are not supported
+
+___
+[Table of Contents](#toc)
+
+Tables
+------
+
+Simple tables are easily generated
+
+|         |* Col 1  *|* Col 2 *|
+|* Row 1 *| (1, 1)   | (1, 2)   |
+|* Row 2 *| (2, 1)   | (2, 2)   |
+
+**Note:** Nested tables are not supported
+
+___
+[Table of Contents](#toc)
+
+Images
+------
+
+`txt2lrf` also has support for inline images like 
+![this one](../../html/demo/small.jpg) this one. 
+
+___
+[Table of Contents](#toc)
+
+Automatic TOC Creation
+----------------------
+
+By inserting `///Table of Contents///` into the text at some point 
+a table of contents is automatically generated with links that point 
+to all headings underlined with `-------`.
+
+___
+[Table of Contents](#toc)
+