[#4] Checkstyle reverted to 9.3 because of Java8 compatiblity.

Author: DjThunder

b3dgs-parent/pom.xml

@@ -115,7 +115,7 @@
         <maven-resources.version>3.3.0</maven-resources.version>
         <maven-dependency.version>3.5.0</maven-dependency.version>
         <maven-release.version>3.0.0-M7</maven-release.version>
-        <checkstyle.version>10.4</checkstyle.version>
+        <checkstyle.version>9.3</checkstyle.version>
         <pde-target-maven.version>1.0.1</pde-target-maven.version>
         <maven-gpg.version>3.0.1</maven-gpg.version>
         <maven-jarsigner.version>3.0.0</maven-jarsigner.version>