Upgraded site, cobertura and checkstyle plugins.
Further updates of plugins.
maven-project-info-reports-plugin enabled by default.
Configured assembly target to create a zip.
The assembly needed for the source packaging.
Removed non-html-compliant email addresses.
Fix to javadoc.
Merge pull request #14 from SERG-Delft/maven-versions

Maven versions
Creating a test jar
Merge pull request #15 from SERG-Delft/javadoc

Updating some javadoc
Merge pull request #17 from SERG-Delft/creating-test-jar

Creating a test jar
Strengthened invariants.
Merge pull request #18 from SERG-Delft/invariants

Strengthened invariants.