* Spotbugs, PMD and Checkstyle #33

* Reducing Spotbugs effort to min #33



 * Also using project.parent.basedir and avoiding relative paths in pom files.
 * Filtering out samples.

* Move PMD/Spotbugs to static-analysis profile

This moves the static-analysis checks to a standalone profile. Core
contributors may run static analysis with:

```
mvn -Pstatic-analysis install
```

The analysis is separated from default functionality to reduce impact to
community contributions. SpotBugs/PMD may add a non-trivial amount of
time to builds on some machines.

Co-authored-by: Tomas Bjerre <tomas.bjerre85@gmail.com>