Modify build files to use Java8

DataCompressor.iml

 <?xml version="1.0" encoding="UTF-8"?>
-<module type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_9">
+<module org.jetbrains.idea.maven.project.MavenProjectsManager.isMavenModule="true" type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_8">
     <output url="file://$MODULE_DIR$/target/classes" />
     <output-test url="file://$MODULE_DIR$/target/test-classes" />
     <content url="file://$MODULE_DIR$">
@@ -11,29 +11,6 @@
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
     <orderEntry type="library" exported="" name="Maven: org.jetbrains:annotations:18.0.0" level="project" />
-    <orderEntry type="library" name="Maven: org.apache.commons:commons-math3:3.6.1" level="project" />
-    <orderEntry type="library" name="Maven: commons-cli:commons-cli:1.4" level="project" />
-    <orderEntry type="library" exported="" name="Maven: org.jetbrains:annotations:19.0.0" level="project" />
-    <orderEntry type="library" exported="" name="Maven: com.google.code.gson:gson:2.8.6" level="project" />
-    <orderEntry type="library" exported="" name="Maven: io.scif:scifio:0.37.3" level="project" />
-    <orderEntry type="library" exported="" name="Maven: io.scif:scifio-jai-imageio:1.1.1" level="project" />
-    <orderEntry type="library" exported="" name="Maven: net.imagej:imagej-common:0.28.2" level="project" />
-    <orderEntry type="library" exported="" name="Maven: net.imglib2:imglib2-roi:0.7.0" level="project" />
-    <orderEntry type="library" exported="" name="Maven: net.imglib2:imglib2-realtransform:2.2.1" level="project" />
-    <orderEntry type="library" name="Maven: gov.nist.math:jama:1.0.3" level="project" />
-    <orderEntry type="library" exported="" name="Maven: jitk:jitk-tps:3.0.1" level="project" />
-    <orderEntry type="library" name="Maven: com.googlecode.efficient-java-matrix-library:ejml:0.24" level="project" />
-    <orderEntry type="library" name="Maven: log4j:log4j:1.2.17" level="project" />
-    <orderEntry type="library" name="Maven: net.sf.trove4j:trove4j:3.0.3" level="project" />
-    <orderEntry type="library" exported="" name="Maven: org.scijava:scijava-table:0.4.0" level="project" />
-    <orderEntry type="library" name="Maven: edu.ucar:udunits:4.3.18" level="project" />
-    <orderEntry type="library" exported="" name="Maven: net.imglib2:imglib2:5.6.3" level="project" />
-    <orderEntry type="library" exported="" name="Maven: net.imglib2:imglib2-cache:1.0.0-beta-11" level="project" />
-    <orderEntry type="library" exported="" name="Maven: com.github.ben-manes.caffeine:caffeine:2.4.0" level="project" />
-    <orderEntry type="library" exported="" name="Maven: org.scijava:scijava-common:2.77.0" level="project" />
-    <orderEntry type="library" exported="" name="Maven: org.scijava:parsington:1.0.4" level="project" />
-    <orderEntry type="library" name="Maven: org.bushe:eventbus:1.4" level="project" />
-    <orderEntry type="library" name="Maven: commons-io:commons-io:2.6" level="project" />
     <orderEntry type="library" name="Maven: io.scif:scifio:0.31.0" level="project" />
     <orderEntry type="module-library">
       <library>
@@ -45,5 +22,28 @@
       </library>
     </orderEntry>
     <orderEntry type="library" name="Maven: net.imagej:ij:1.51g" level="project" />
+    <orderEntry type="library" name="Maven: org.apache.commons:commons-math3:3.6.1" level="project" />
+    <orderEntry type="library" name="Maven: commons-cli:commons-cli:1.4" level="project" />
+    <orderEntry type="library" name="Maven: org.jetbrains:annotations:19.0.0" level="project" />
+    <orderEntry type="library" name="Maven: com.google.code.gson:gson:2.8.6" level="project" />
+    <orderEntry type="library" name="Maven: io.scif:scifio:0.37.3" level="project" />
+    <orderEntry type="library" name="Maven: io.scif:scifio-jai-imageio:1.1.1" level="project" />
+    <orderEntry type="library" name="Maven: net.imagej:imagej-common:0.28.2" level="project" />
+    <orderEntry type="library" name="Maven: net.imglib2:imglib2-roi:0.7.0" level="project" />
+    <orderEntry type="library" name="Maven: net.imglib2:imglib2-realtransform:2.2.1" level="project" />
+    <orderEntry type="library" name="Maven: gov.nist.math:jama:1.0.3" level="project" />
+    <orderEntry type="library" name="Maven: jitk:jitk-tps:3.0.1" level="project" />
+    <orderEntry type="library" name="Maven: com.googlecode.efficient-java-matrix-library:ejml:0.24" level="project" />
+    <orderEntry type="library" name="Maven: log4j:log4j:1.2.17" level="project" />
+    <orderEntry type="library" name="Maven: net.sf.trove4j:trove4j:3.0.3" level="project" />
+    <orderEntry type="library" name="Maven: org.scijava:scijava-table:0.4.0" level="project" />
+    <orderEntry type="library" name="Maven: edu.ucar:udunits:4.3.18" level="project" />
+    <orderEntry type="library" name="Maven: net.imglib2:imglib2:5.6.3" level="project" />
+    <orderEntry type="library" name="Maven: net.imglib2:imglib2-cache:1.0.0-beta-11" level="project" />
+    <orderEntry type="library" name="Maven: com.github.ben-manes.caffeine:caffeine:2.4.0" level="project" />
+    <orderEntry type="library" name="Maven: org.scijava:scijava-common:2.77.0" level="project" />
+    <orderEntry type="library" name="Maven: org.scijava:parsington:1.0.4" level="project" />
+    <orderEntry type="library" name="Maven: org.bushe:eventbus:1.4" level="project" />
+    <orderEntry type="library" name="Maven: commons-io:commons-io:2.6" level="project" />
   </component>
 </module>
\ No newline at end of file

pom.xml

@@ -22,8 +22,8 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
-                    <source>9</source>
-                    <target>9</target>
+                    <source>8</source>
+                    <target>8</target>
                 </configuration>
             </plugin>
         </plugins>