range_extd 0.1.0

This defines a subclass of Range, RangeExtd and its subclass, RangeExtd::Infinity. The former defines a range that enables an exclusion of the begin boundary, in addition to the end boundary as in the built-in Range, and accepts open-ended ranges to infinity for either (or both) positive/negative direction. The latter has the two constant objects, POSITIVE and NEGATIVE, and they are a generalised Infinity of Float::INFINITY to any Comparable objects.