Filter 'Node: Author Name (text field)'

The filter 'Node: Author Name' provides a drop down list of author names. While this is very useful if you don't have a lot of users, for large sites the list becomes overpopulated. In that case, it might be better to use a text field, which would allow a user to type in the author's name, instead of selecting it from the drop down. I'm attaching the patch, which provides two filters:

• 'Node: Author Name (drop down)' - i.e. the original one, which is suitable for sites with only a few users
• 'Node: Author Name (text field)' - appropriate for sites with a large number of users