Move parameter logic to AbstractConsoleArgument

The AbstractConsoleArgument already had a protected isFlag method;
for consistently, let's just put single parameter extraction there too.

Author: ctrueden

src/main/java/org/scijava/console/AbstractConsoleArgument.java

@@ -86,4 +86,17 @@ public Class<LinkedList<String>> getType() {
 	protected boolean isFlag(final LinkedList<String> args) {
 		return flags.isEmpty() || flags.contains(args.getFirst());
 	}
+
+	/**
+	 * If the next argument is an appropriate parameter to a
+	 * {@link ConsoleArgument}, retrieves it; otherwise, returns null.
+	 *
+	 * @return The first argument of the given list, if it does not
+	 *         start with a {@code '-'} character; or null otherwise.
+	 */
+	protected String getParam(final LinkedList<String> args) {
+		if (args.isEmpty()) return null;
+		final String arg = args.getFirst();
+		return arg.startsWith("-") ? null : arg;
+	}
 }

src/main/java/org/scijava/run/console/RunArgument.java

@@ -75,7 +75,7 @@ public void handle(final LinkedList<String> args) {
 
 		args.removeFirst(); // --run
 		final String code = args.removeFirst();
-		final String arg = ConsoleUtils.hasParam(args) ? args.removeFirst() : null;
+		final String arg = getParam(args);
 
 		final Items items = parser.parse(arg);
 		try {