Various issues: permissions, string replacement, page output

Issue Summary

This patch is covering few issues I ran into.
While submitting one patch for several issues isn't the preferred method in Drupal, I rather doing it so, than not submitting a patch at all. Here goes:

• I modified the viewing permissions. There is a "view all favorite nodes" and "view own favorite nodes", so one can limit viewing favorite nodes only to the current user.
• Allow viewing of all favorite nodes, without specifying the type
• Allow a clean url (without uid ot type) to view own favorite nodes
• Replaced print theme('page', $output); by a simple return $output; in the page function
• Fixed wrong variable replacement in t() functions

This patch can be improved, but I think it is good enough, as is, to render the module just a bit more correct, syntax-wise.