Just reformat 'posts' field
Fix #248, #249, also [link](http://www.deluxeblogtips.com/forums/viewtopic.php?id=422)
Shorten checks when saving posts:
- revert check for autosave, using constants. The function `wp_is_post_autosave` is not realiable when current post is Draft
- remove check for user permission, as WP already does that
- remove check for inline-save as verifying nonce is enough

Note: nonce now is verified only, no "permission" nag is displayed when it's invalid. We just return in that case. This won't block other code to execute.