Previously CPTableView -_init was trying to reference a theme value, but that doesn't work because the theme creates a CPTableView and during that _init the theme value is not yet defined.
This commit uses lazy instantiation to avoid this problem.
Also, column selection was added to the CPDictionaryControllerTest to better visualize unfocused selection highlight colors.
CPTableView has no focus ring, and currently gives no visual feedback of its firstResponder status. In Cocoa when the table view resigns firstResponder or its window loses key status, the selection color turns gray.
This commit sets the selection color to gray when a table view resign firstResponder or its window loses key status. A second window and a couple of textfields were added to the CPDictionaryControllerTest to demonstrate the changes.
Fixes#1839