- added fix when using the plot in a knitr document
- added the possibility to use node labels
- added options for formatting node labels
- added title and subtitle management
- enhance layout management
- enhance legend management
- switch to 0.2.0

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/spnet@13 edb9625f-4e0d-4859-8d74-9fd3b1da38cb