Comments/ASDoc entry for pdf.setAlpha are incorrect

```
The comments for the pdf.setAlpha function are incorrect, they seem to be a 
copy of 
aliasNbPagesMethodMethod's comments.

This means the incorrect description and examples for setAlpha feed through 
into the ASDocs too.

Would submit a fix, but I'm unsure of what the "bm" parameter is for!
```

Original issue reported on code.google.com by `imijsoft` on 10 Sep 2007 at 9:45
