able to do different options for titles

I started trying to get the header.type incorporated in all the necessary places for function calls, and based on my current understanding of the code, gave up, due to some of the ways things are nested.

Instead, I end up depending on the declaration of a global variable `header.type` in the sourcing of `config.R`, and then the function evaluates that for the switch. I've tested it by creating two different blogs, and it appears to work at extracting the titles. I don't like it, but for a quick fix it works. It was either that or have the user go in and modify the source to change the default if they wanted to use the `#` sign for first level headers. I understand if you don't merge this one, as I said it is a little bit hackish to depend a global variable, and will probably break.