Fix double free in display dialog (#1053)
Fix double free in display dialog (#1053)

This commit deletes AddDisplayDialog object after use.

Copy operator of QString in rviz::AddDisplayDialog::updateDisplay() causes double free AFTER CLOSING THE DIALOG.
Since AddDisplayDialog object created in DisplaysPanel::onNewDisplay never deleted, local variable topic_output could be overwritten after leaving local scope.
This seems to have occurred especially in many-core (16-physical-core in my case) environments.
ros-visualization/rviz,ros-visualization/rviz,ros-visualization/rviz,ros-visualization/rviz,ros-visualization/rviz