Normalize newlines to '\n'

Change all \r\n into unix style newlines. Add missing newlines at the
end of a file and activate the newline checkstyle module, that enforces
'\n' as newline and a newline at the end of every file.

config/checkstyle.xml

@@ -11,6 +11,9 @@
 		<property name="ignoreLines" value="3"/>
 		<property name="fileExtensions" value="java"/>
 	</module>
+	<module name="NewlineAtEndOfFile">
+		<property name="lineSeparator" value="lf"/>
+	</module>
 	<module name="TreeWalker">
 		<module name="UnusedImports">
 			<property name="processJavadoc" value="true"/>