Make anchors better when using TOC

Hi,

Multimarkdown is a wonderful piece of software and it works as advertised. I wanted to file this idea for an improvement of handling table of contents (TOC) anchors when exporting to HTML.

Currently, all TOC anchors are quite plain and there is no processing at this time in multimarkdown. While i can understand that action, it leaves the anchors a bit plain. Example of an anchor, from one HTML page:

```
foo.bar/index.html#Firstparagraph
```

Now prom the usability aspect, we should have something more like
```
foo.bar/index.html#first-paragraph
```

Now from semantic point of view, it would be neat to have an option to process these anchors a bit. Pandoc does it quite good and can be used as an example:

- all letters are lowercase
- all anchors wave dash (`-`) instead of space
- you can set TOC title, which will be omitted from the TOC list

Is it possible to think about this and implement it in the future? Thank you.