replaced stdev() with stDevPopulation() and stDevSample(); added _stdev() private method; fixed omissions in keywords.txt; added new methods to keywords.txt; corrected examples and tests --KW
fixed compile time error in Filter.cpp; removed failing unit test from test.ino temporarily --KW
fixed integer overflow error in _stDev() --KW
minor formatting change --KW
added tests for stDevSample() --KW