Change unit for printing a dimensionless SiScalar to be blank

[averbraeck]

Currently, a dimensionless SIScalar prints a unit of '1'. Now that the Dimensionless prints a blank unit, the SIScalar has to be changed as well to be consistent. As an example, the following code:

  SIScalar s1 = Torque.of(1.33, "N.m").divide(Energy.valueOf("2.1 J"));
  System.out.println("|" + s1 + "|");

prints:

|0.63333333 1|

[averbraeck]

The code:

  SIScalar s1 = Torque.of(1.33, "N.m").divide(Energy.valueOf("2.1 J"));
  System.out.println("|" + s1 + "|");

now displays:

|0.63333333 |

A demo called DimensionlessExample has been added to the djunits-demo project to show the parsing and printing of Dimensionless and FloatDimensionless scalars, as well as SIScalar and FloatSIScalar where the SI dimensions are 1. Examples for Vector, FloatVector, SIVector and FloatSIVector are also included.

[averbraeck]

A helper static constant for the SIUnit class called DIMLESS is added. It is the DIMLESS is defined as the SIUnit with all dimensions equal to zero:

  SIUnit DIMLESS = SIUnit.of(new SIDimensions(0, 0, 0, 0, 0, 0, 0, 0, 0));

[averbraeck]

All 283 unit tests pass again after the changes of the SIDimensions and SIUnit to accept and print an empty string for a dimensionless quantity.

[averbraeck]

The following changes have been made:

• DimensionlessUnit has an empty string as the default unit id and unit name.
• Dimensionless can parse an empty string as the unit in the of(...) and valueOf(...) methods
• FloatDimensionless can parse an empty string as the unit in the of(...) and valueOf(...) methods
• SIDimensions accepts an empty string as the unit in the of(...) and parse(...) methods
• SIDimensions has a static constant called DIMLESS to indicate a dimensionless SI tuple
• SIUnit has a static constant called DIMLESS to indicate a dimensionless SI unit
• SIScalar accepts an empty string as the unit in the of(...) and valueOf(...) methods
• FloatSIScalar accepts an empty string as the unit in the of(...) and valueOf(...) methods
• SIVector can parse an empty string as the unit in the three of(...) methods
• FloatSIVector can parse an empty string as the unit in the three of(...) methods
• SIMatrix can parse an empty string as the unit in the of(...) method
• FloatSIMatrix can parse an empty string as the unit in the of(...) method
• A demo called DimensionlessExample has been added to the djunits-demo project
• All generating classes and templates in the djunits-generator project have been adapted
• All unit tests in the djunits project have been updated with the new behavior for dimensionless SI values

This covers all known issues with dimensionless SI values to not print or use '1' anymore as the unit, but leave it blank in the exact way that Dimensionless now prints it unit after Issue #12 was completed.