Fix typos

Fixed some typos in comments and test strings.

There are two more possible misspellings in History.md (L346 and L347):

> Added raises assertion, reusing some of kennsnyder's code.
> Merged kensnyder's object detection code. Original message: Streamlined object detection and exposed QUnit.objectType as a function.

kennsnyder and kensnyder -- not sure whats the correct version, may be both of them :)