Edit code comments for comprehension

The American Civil War happened during the 1860's
Latex format

Ok no problem it's back on Latex.  As for the accent, it seems like the entire doc should either be with it or without it, not both.  As it is, the accent was only used in about 1 or 2 places and not used almost everywhere else.  Some sites use it, some don't.
UTF-8 encoding

UTF-8 encoding enabled in this file.  Allows properly writing 'Vigenère' for that cipher section.
Edit in that section header

Updated 'Vigenère' in that section header as well
Remove UTF related comment at top of file
Merge pull request #7373 from richierichrawr/master

Typofix -- Edit code comments for comprehension
Add richierichrawr to the AUTHORS/aboutus. Welcome to SymPy!