attributes for tab link

Hi,

Thanks for this awesome module. In the current version, The class attribute for the tab links are constructed from title of the tab.

It will be really helpful, if the array returned by callback can configure these attributes. Right now the array has two elements for each tab 'title' and 'content'. is it good to add a third element called 'attribute' (same as the attribute array accepted by l() function)

scenarios where this is needed:

I have a tabset where the tab titles are all images (no text). And i would like to have all the tab title images in a css sprite. In this case, i can leave the title blank and set the attributes. Using css i can assign the images.

thanks
Manny