:normalize_whitespace_cdata as new Options

 Add a new Option :normalize_whitespace_cdata for normalization in textnode, that there is a diffrent between normal whitespace in the stucture and text. This option add to DEFAULT_OPTS with the value false.

I find it better that there are 2 different ways to noramilize whitespace. I hope the description/rdoc are right now, too^^.

Thx for your work