Added option "stripBrs" ("Ignore <br> tags")

Sorry, only tested it with one-line code snippets. When using multi-line code snippets, my s9y Installation added &lt;br&gt; tags after each line which the plugin showed as &lt;br&gt; (literally) in the blog entry.
So I added the option "stripBrs" which can be enabled to ignore these tags.

Because I have only one s9y Installation, I'm not brave enough to enable this option as default ;)