Add Strikethrough

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Make a new file in the testfiles directory
2. put a line and strike it with ~. ex: ~~this should be striked~~
3. run the sample

What is the expected output? What do you see instead?

I would expect to see the <s></s> tags surrounding 'this should be striked'


What version of the product are you using? On what operating system?

v1.13
Windows 8
VS 2012
.NET 3.5

Please provide any additional information below.

Original issue reported on code.google.com by aschiav...@internationalyouthcongress.org on 5 Sep 2013 at 2:58