+ update version 0.2.04
+ added getElement() (not released 0.2.03 version)
+ added getSize()    (not released 0.2.03 version)
+ added getCount()   (not released 0.2.03 version)
+ updated keywords.txt
+ added memory protection if there is not enough memory to allocate.
+ added return NAN instead of 0  for getAverage()
+ reduced _size, _cnt, _idx to uint8_t
+ changed extensions of example code to .ino