Typo "oberveValueForKeyPath:" in NSKeyValueObserving

[Ivan Vučica]

Hey Richard,

See "oberveValueForKeyPath:" appear here:

  https://github.com/gnustep/base/blob/master/Source/NSKeyValueObserving.m#L1373

This happened in commit 39958

  https://github.com/gnustep/base/commit/6713bb48d6018c6f949a56128c07fea5f222d41f

I don't have my credentials with me to fix this right now. I also don't know if this was an intentional change to temporarily make something stop working.