Using named HTML entites rather than straight-up UTF-8 characters

I noticed that the characters don't show up nicely on non-UTF-8 compliant systems. So changed the original UTF-8 characters mapped to named HTML entities sourced from [Wikipedia](http://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references).

Commands run to generate this change:
```
sed -i 's/←/\&larr;/' *
sed -i 's/→/\&rarr;/' *
sed -i 's/×/\&times;/' *
```