Added handling of -h/--help CLI option, to print out available options. (#22)

Small CLI improvement: adding a -h / --help switch, to be able to get a printout of the available options.

Reviewed-on: https://codeberg.org/sethm/symon/pulls/22
Reviewed-by: Seth Morabito <sethm@noreply.codeberg.org>

src/main/java/com/loomcom/symon/Main.java

@@ -49,6 +49,7 @@ public class Main {
 
         Options options = new Options();
 
+        options.addOption(new Option("h", "help", false, "Print this message."));
         options.addOption(new Option("m", "machine", true, "Specify machine type."));
         options.addOption(new Option("c", "cpu", true, "Specify CPU type."));
         options.addOption(new Option("r", "rom", true, "Specify ROM file."));
@@ -62,6 +63,12 @@ public class Main {
             String romFile = null;
             boolean haltOnBreak = false;
 
+            if (line.hasOption("help")) {
+                HelpFormatter formatter = new HelpFormatter();
+                formatter.printHelp("symon", options, false);
+                return;
+            }
+
             if (line.hasOption("machine")) {
                 String machine = line.getOptionValue("machine").toLowerCase(Locale.ENGLISH);
                 switch (machine) {
@@ -121,7 +128,6 @@ public class Main {
                             possibilities,
                             "Symon");
 
-
                     if (s != null && s.equals("Multicomp")) {
                         machineClass = MulticompMachine.class;
                     } else if (s != null && s.equals("Simple")) {
@@ -150,7 +156,6 @@ public class Main {
                     }
                 });
 
-
                 Simulator.MainCommand cmd = simulator.waitForCommand();
 
                 if (cmd.equals(Simulator.MainCommand.SELECTMACHINE)) {