Refactor: Distance

[Segelzwerg]

• use units: kilometer, miles and nauticals with each having two final interger field for the major and minor unit

• create Factory Class(es) Move static method in Distance to Factory class #77

• do not allow fields to be changed

  SportToolBox/src/main/java/segelzwerg/sporttooolbox/iunits/Distance.java

  Lines 29 to 34 in a072e47

  	public Distance(float kilometer) {
  	this(kilometer, 0);
  	if (kilometer < 0.0) {
  	throw new IllegalArgumentException();
  	}
  	}

• change Distance to Interface

• create distance package in iunit

• create conversion methods for different distance units Add Conversion of all distance units #87

relies on #71