BUG: WordCloud did not reserve string length

Before transforming the skippedWord string, the string was not resized
to the length of the skippedWord. This caused some platforms to report
1 skipped word, while other platforms crashed. The UnitTestWordCloud
is updated to reflect the properly calculated skipped words.

Thanks to Ken for finding this bug.

 LocalWords:  WordCloudBug Infovis ThirdParty vtkEventData
 LocalWords:  vtkGenericOpenGLRenderWindow