Added highlight/border around input box with invalid input (defined as an input for a named image window with a name that already exists)
Added highlight/border around input box with invalid input (defined as an input for a named image window with a name that already exists)
Removed extraneous opencvimagewindow.h header
Added code to handle a weird edge case where on a Mac the camera devices weren't being properly reported; added Source and Output dock widgets to the Main Window; hooked up window menu to show/hide docked widgets