Update .gitignore to ignore Maven files.

.gitignore

@@ -32,6 +32,19 @@ hs_err_pid*
 # Syncthing being weird
 .syncthing.*
 
+# ---> Maven
+target/
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
+pom.xml.next
+release.properties
+dependency-reduced-pom.xml
+buildNumber.properties
+.mvn/timing.properties
+# https://github.com/takari/maven-wrapper#usage-without-binary-jar
+.mvn/wrapper/maven-wrapper.jar
+
 # Netbeans
 **/nbproject/private/
 **/nbproject/Makefile-*.mk