Ignore embedded PHP and other code

[avdgaag]

Typogruby might incorrectly mess with embbed code in a page. It should probably include an option to enable agressive ignoring, so to speak: ignore anything between tags like <?php, <%= etc. This might give it a performance hit — and it is probably a rare use case — so making it non-default would be sensible.

On a related note, using Typogruby as a Ruby library instead of from the command line, it would be nice to set a list of patterns to ignore.