Esc key should close the link panel even if none of the LinkFormView fields is focused. Closes #90. (866fa49)
The link balloon should hide the "Unlink" button when creating a link. Closes #53. (686e625)
The link balloon should update its position upon external document changes. Closes #113. (18a5b90)
The link plugin should manage focus when the balloon is open. Made Link plugins _showPanel() and _hidePanel() methods protected. Closes #95. Closes #94. (5a83b70)
Link should not be allowed directly in the root element. Closes #97. (81d4ba5)
Other changes
Integrated the link plugin with the ContextualBalloon plugin. Closes #91. (26f148e)