Add flag for ignoring whitespace on evaluation

[duckth]

When Kattis evaluates output, these are identical:

Kattis is "whitespace-agnostic", so to say - it doesn't matter if it is a space or a newline character, as long as there is some whitespace. Kitty is not, and treats this as test failure. They should test in the same way.

As this may or may not be true in all cases, a flag for treating these outputs the same way would be preferable.