Allow target="" in links by default

[wpdennis]

The editor is showing the checkbox "Open link in a new window/tab" in its add link popup, by default.

But using it doesn't work for participants, since target="" isn't allowed. It would be more consistent to allow it by default or to remove the checkbox from the add link popup.

Allowing it in ​formatting.php:

// Links
'a' => array(
		'href'     => array(),
		'title'    => array(),
		'rel'      => array(),
		'target'      => array()
),

[johnjamesjacoby]

In 5205:

Add target to anchor in bbp_kses_allowed_tags(). Props wpdennis. Fixes #2483. (trunk)

[johnjamesjacoby]

In 5206:

Add target to anchor in bbp_kses_allowed_tags(). Props wpdennis. Fixes #2483. (2.5)

[johnjamesjacoby]

In 5220:

In bbp_kses_allowed_tags() use true instead of empty array() for individual tag attributes. Props netweb. See #2483.