Added the ability to open an image link in a target selected

Added the ability to open an image link in target selected.
This way we can open image links in a new window, or in a parent frame, own frame or top frame.

This will make the image block a lot more usefull in a lot of situations. Like using it for logo's.

Added a line in the blocks db.xml (openLinkAs type="C" size="255")
Size is 255 so it doesn't have to be changed if someone changes the select to a input so they can put their own frame name in.

Also added a few lines in the core image block controller so we can display the target.

Also added the select box to the form file in the image block folder, so we can select the target.

Also added a line in auto.js. This is used to toggle the select box.

Related to https://github.com/concrete5/concrete5/pull/944