Title processing changes

Fixed two bugs which make the inheritance of titles much more natural

1st: If the content did not have a "head" tag, the decorator title would not be processed leaving the title blank. I updated the code to properly process the decorator title when the content head is null

2nd: When either the decorator title or content title are empty, the title pattern is being processed which is resulting in unnatural titles such as "Decorator Title -" instead of "Decorator Title". I updated the code to only process the title pattern if both decorator title and content title are not empty

Thanks for the great plugin!

- Justin