Incorrect check for max_items limit

Thanks for this module, I've used and customized it quite a bit in a recent project. :)

Though I haven't used the max items feature, I think there is a bug in it.

Instead of this:

if (!empty($max_items) && count($oids) == $max_items)

I think you wanted this:

if (!empty($max_items) && count($oids) > $max_items)

A few extra stuff:

1. I think it would be really friendly to only display this message to admins (i.e. user_access('administer views') check).

2. I don't think the code actually limits the amount of total results. Either the message should be updated to be just a notification about exceeding $max_limits or $oids should be actually reduced, e.g. with array_slice.

3. Moving this entire logic into its own method would make the already pretty long get_oids() method a bit easier to read. Also people extending this class will need to worry about a bit less code.

I'd be happy to update the patch if you think any of these make sense.