Resolve "Fix versioning and prepare publishing"

Closes #23 (closed)

src/main/java/org/jastadd/relast/compiler/Compiler.java

@@ -23,6 +23,7 @@ public class Compiler {
   private FlagOption optionResolverHelper;
   private FlagOption optionUseJastaddNames;
   private FlagOption optionQuiet;
+  private FlagOption optionVersion;
   private CommandLine commandLine;
 
   public Compiler(String[] args) throws CommandLineException {
@@ -32,6 +33,11 @@ public class Compiler {
     commandLine = new CommandLine(options);
     commandLine.parse(args);
 
+    if (optionVersion.isSet()) {
+      System.out.println(readVersion());
+      return;
+    }
+
     printMessage("Running RelAST " + readVersion());
 
     if (commandLine.getArguments().size() < 1) {
@@ -179,6 +185,7 @@ public class Compiler {
     optionUseJastaddNames = addOption(new FlagOption("useJastAddNames", "generate names in the form of addX, removeX and setX. If omitted, the default, original naming scheme resulting in addToX, removeFromX and setX will be used."));
     optionSerializer = addOption(new EnumOption("serializer", "generate a (de-)serializer", Arrays.asList("jackson", "jackson-json-pointer", "jackson-manual-references"), "jackson"));
     optionQuiet = addOption(new FlagOption("quiet", "do not output anything on stdout"));
+    optionVersion = addOption(new FlagOption("version", "print version and exit"));
   }
 
   private <OptionType extends Option<?>> OptionType addOption(OptionType option) {