The constructor performed two things simultaniously,
which is not good for a ctor: Constructing the object
and calculating the values at given points.

If needed such code should be moved to a standalone
algorithm.

This way an expensive copy must be performed by the
caller and is not hidden in the ctor.

Reasoning: The vector's move operation is cheap and it covers the two cases of
passed l-values and r-values w/o code duplication and templates.

According to "Effective modern c++" Item 41: "Consider pass by value for
copyable parameters that are cheap to move and always copied."

If the point to interpolate the value on is not located in any interval we choose either the first or the last interval and extrapolate the data. The algorithm for the determination of the interval is corrected.

This reverts commit 05677165.

Conflicts:
	FileIO/XmlIO/XmlGspInterface.cpp
	README.md

- added class template LinearIntervalInterpolation