Release guidlines

To create a new release of PDBF the following steps have to be done:

• Change version number in pom.xml, VERSION.md, README.md
• Create reference pictures (java -jar pdbf.jar --create-reference-images)
• Verify that there are no errors when executing mvn verify on Windows, Linux, and Mac
• Merge dev branch into gh-pages branch
• Create a new release on github (https://github.com/uds-datalab/PDBF/releases/new)
• prepare zip for new release on CTAN (https://raw.githubusercontent.com/uds-datalab/PDBF/gh-pages/prepare-ctan-submit.sh)
• Create a new relase on CTAN (visit https://www.ctan.org/pkg/pdbf-toolkit and click upload)