Lenient mode for extracting annotations

[remkop]

Needed for #258.

CommandSpec.forAnnotatedObject requires at least one picocli annotation on the specified object.

To allow mixing groovy.cli and picocli annotations, a factory method is needed that allows picocli annotation to be optional.

[remkop]

Index: src/test/java/picocli/CommandLineModelTest.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/test/java/picocli/CommandLineModelTest.java	(revision )
+++ src/test/java/picocli/CommandLineModelTest.java	(revision )
@@ -906,4 +906,37 @@
         assertTrue(spec.options().isEmpty());
         assertFalse(spec.mixinStandardHelpOptions());
     }
+
+    @Test
+    public void testCommandSpec_forAnnotatedObject_requiresPicocliAnnotation() {
+        try {
+            CommandSpec.forAnnotatedObject(new Object());
+            fail("Expected error");
+        } catch (InitializationException ok) {
+            assertEquals("java.lang.Object is not a command: it has no @Command, @Option, @Parameters or @Unmatched annotations", ok.getMessage());
+        }
+    }
+
+    @Test
+    public void testCommandSpec_forAnnotatedObjectLenient_doesNotRequirePicocliAnnotation() {
+        CommandSpec.forAnnotatedObjectLenient(new Object()); // no error
+    }
+
+    @Test
+    public void testCommandSpec_forAnnotatedObjectLenient_returnsEmptyCommandSpec() {
+        CommandSpec spec = CommandSpec.forAnnotatedObjectLenient(new Object());
+        assertTrue(spec.optionsMap().isEmpty());
+        assertTrue(spec.posixOptionsMap().isEmpty());
+        assertTrue(spec.options().isEmpty());
+        assertTrue(spec.positionalParameters().isEmpty());
+        assertTrue(spec.unmatchedArgsBindings().isEmpty());
+        assertTrue(spec.subcommands().isEmpty());
+        assertTrue(spec.mixins().isEmpty());
+        assertTrue(spec.requiredArgs().isEmpty());
+        assertFalse(spec.mixinStandardHelpOptions());
+        assertFalse(spec.helpCommand());
+        assertEquals("<main class>", spec.name());
+        assertArrayEquals(new String[0], spec.version());
+        assertNull(spec.versionProvider());
+    }
 }