Support Swype IME backspace key.

Thanks to Julian Brost (who fixed the same bug in the connectbot project),
and thanks to Todd Musall for spotting the bug fix in the connectbot
tracker, and tried it out in Android Term.

In general we now support any IME trying to delete text to the left of
the cursor by calling InputConnector.deleteSurroundingText(). We generate
one "del" key event for each character of text that is to be deleted.

We don't support deleting text to the right of the cursor. If this
becomes an issue we can experiment with forward-cursor followed by del.

AndroidManifest.xml

@@ -1,6 +1,6 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="jackpal.androidterm"
-      android:versionName="1.0.14" android:versionCode="15">
+      android:versionName="1.0.15" android:versionCode="16">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
     <application android:icon="@drawable/app_terminal"

src/jackpal/androidterm/Term.java

@@ -2809,6 +2809,16 @@ class EmulatorView extends View implements GestureDetector.OnGestureListener {
                 return true;
             }
 
+            @Override
+            public boolean deleteSurroundingText(int leftLength, int rightLength) {
+                for (int i = 0; i < leftLength; i++) {
+                    sendKeyEvent(
+                            new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_DEL));
+                }
+                // TODO: handle forward deletes.
+                return true;
+            }
+
             private void sendChar(int c) {
                 try {
                     mapAndSend(c);