* Version 0.6-1

- added function testData to generate samples for creating piper
  objects

- removed 'WaterType' and 'object' slots on piper objects because
  the concept was buggy.  Better to assign pch and col parameters
  directly, example changed to reflect this.

- fixed default pch and col assignment so more than 26 samples does
  not cause an error

* Version 0.5-1

- allowed use of `cex' parameter in piper diagrams

* Version 0.4-1

- fixed a bug that plotted points in the wrong places

* Version 0.2-3

- fixed a bug whereby cex parameter could not be used

* Version 0.2-2

- major rewrite as S4 classes