Add cenity functionality to handle ok-label and cancel-label

[greygoo]

This change:

• Adds handling of ok-label and cancel-label by the cli interface
• Fixes the tests to work with the changed output layout
• Disables the automatic tik_progress test which was unreliable and hackish and failed with the label changes
• Adds a simple manual tik_progress test, that makes comparing progress output with from cenity with zenity easier
• Adds output and diff mode to the cenity test framework, so it's easier to generate all cli interfaces for manual inspection