IDEA-64964 Javadoc: Provide ability to configure IntelliJ IDEA to automatically insert closing tags during typing in javadoc

1. Javadoc typed handler with 'auto insert closing tag' logic is added;
2. Corresponding test is added;
3. Corresponding GUI control is provided;

java/java-impl/testSrc/com/intellij/codeInsight/editorActions/JavadocTypedHandlerTest.java

@@ -0,0 +1,48 @@
+package com.intellij.codeInsight.editorActions;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author Denis Zhdanov
+ * @since 02/02/2011
+ */
+public class JavadocTypedHandlerTest {
+
+  private static final String CARET_MARKER = "<caret>";
+  
+  @Test
+  public void correctEmptyTagStart() {
+    doTest("<first></first><second><caret>", "second");
+  }
+  
+  @Test
+  public void standaloneBracket() {
+    doTest("asdf ><caret>", null);
+  }
+
+  @Test
+  public void emptyElement() {
+    doTest("<tag/><caret>", null);
+  }
+
+  @Test
+  public void closingTag() {
+    doTest("<tag></tag><caret>", null);
+  }
+
+  @Test
+  public void startTagOnNewLine() {
+    doTest("<t\nag><caret>", null);
+  }
+  
+  private static void doTest(String text, String expected) {
+    StringBuilder normalized = new StringBuilder();
+    int offset = text.indexOf(CARET_MARKER);
+    normalized.append(text.substring(0, offset));
+    normalized.append(text.substring(offset + CARET_MARKER.length()));
+    CharSequence actual = JavadocTypedHandler.getTagName(normalized.toString(), offset);
+    assertEquals(expected, actual);
+  }
+}