Fix some notices

[nbachiyski]

Last night I turned debugging on and fought with some notices.

In most of the places there are just issets added, but at some places there are more complicated cases, which need review and some testing.

[ryan]

(In [6983]) Notice fixes from nbachiyski. fixes #5961

[fitztrev]

After r6983, the links on my site that used my old permalink structure result in 404s. Prior to this change, the old links would automatically redirect to the new permalink structure and find the post correctly.

[fitztrev]

Reverting the change to wp-inc/canonical.php makes it work.

[ryan]

(In [6998]) Revert changes to canonical that broke redirects. Props fitztrev. fixes #5961

[nbachiyski]

The problem is in these two lines:

$original['query'] = isset($redirect['query'])? $redirect['query'] : false; 
$original['port'] = isset($redirect['port'])? $redirect['port'] : false; 

Here I am filling $original with $redirect's values.

Copy-paste after midnight should be avoided :-)

[andy]

sanitize_post changes broke filtering of new posts, reverted in [7161]