new export features (r13573) needed a lot more work before getting checked in

[Denis-de-Bernardy]

among the problems:

• pending status is still missing from the list
• trash is exported
• newly introduced pre-draft status, or whatever it is, might be exported as well
• might autosaves be exported as well?
• it is not custom post type friendly

... and, of course, it makes one wonder whether there is any point in giving feedback in trac tickets:

​http://core.trac.wordpress.org/ticket/10317#comment:12

[nacin]

Commit early, commit often. There's room for improvements but it's far better than nothing.

Duplicate of #10317.