Add case-insensitive string comparison for $last and $divoutput paramete...

...rs - allows 'y' or 'Y' to be passed and still work!

Found an issue where the 'last' css class was not being added to the sidebar div when specifying the sidebar to be on the right, causing it to drop down beneath the content. The call to wf_css was passing 'y' whereas 'Y' was expected!

Noticed that the option for $divoutput may also hit the same problem, so changed that one too!

Cheers,
Rik