#271 Inconsistent Spelling of Normalizer / Normalizor

[Lemur Project]

Inconsitent spelling of normalizer in RankLib features subdirectory. LinearNormalizer.java, SumNormalizor.java and ZScoreNormalizor.java need to be consistently named. Error messages inside each class need also be consistent in spelling.

Not actually certain of correct spelling. Seems both er and or endings are common, but Google asks if you mean Normalizer when you write Normalizor, so I suppose spelling should standardize on the er form.