Added support for referencing and refactoring inside ``.extracting()`` methods with fields, properties and methods (though getter renaming does not work that perfect, but I'm giving up for now as the IntelliJ SDK docs are seriously lacking).

Fixed an exception in batch mode if the description string was the same but for different fixes. Now descriptions are different for quick fixes triggered by AssertThatJava8OptionalInspection and AssertThatGuavaOptionalInspection. Minor refactorings. Extended documentation.

src/test/resources/references/FindReference1.java

@@ -0,0 +1,15 @@
+import org.assertj.core.extractor.Extractors;
+
+import java.util.Collections;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class FindReference1 {
+
+    private void findReferences() {
+        Contact contact = new Contact();
+
+        assertThat(contact).extracting("name<caret>").isEqualTo("foo");
+    }
+}