RangeOf Comparable<T>

[svendiedrichsen]

@yegor256 Would it be interesting to have a RangeOf implementation for Comparable<T> instances? Example PR follows.

[0crat]

@yegor256 please, pay attention to this issue

[yegor256]

@svendiedrichsen good idea, would be great to have these ctors too:

new RangeOf(1, 10);
new RangeOf(1L, 10L);
new RangeOf('a', 'z');

[yegor256]

@svendiedrichsen maybe we have to delete NaturalNumbers...

[svendiedrichsen]

@yegor256 I have removed NULL handling and added convenience classes/constructors
new RangeOf.Integer(int,int)
new RangeOf.Long(long,long)
new RangeOf.Character(char,char)
Would you like me to remove now obsolete classes NaturalNumbers etc. ?

[yegor256]

@svendiedrichsen yes, NaturalNumbers is not required anymore, let's delete it.

[svendiedrichsen]

@yegor256 done.

[svendiedrichsen]

Changes merged.