Add the ability to clear internal buffers (fixes #910)

reader/src/main/java/org/jline/reader/Buffer.java

@@ -83,4 +83,9 @@ public interface Buffer {
     Buffer copy();
 
     void copyFrom(Buffer buffer);
+
+    /**
+     * Clear any internal buffer.
+     */
+    void zeroOut();
 }

reader/src/main/java/org/jline/reader/LineReader.java

@@ -777,4 +777,9 @@ String readLine(String prompt, String rightPrompt, MaskingCallback maskingCallba
     void setAutosuggestion(SuggestionType type);
 
     SuggestionType getAutosuggestion();
+
+    /**
+     * Clear any internal buffers.
+     */
+    void zeroOut();
 }

reader/src/main/java/org/jline/reader/impl/BufferImpl.java

@@ -8,6 +8,7 @@
  */
 package org.jline.reader.impl;
 
+import java.util.Arrays;
 import java.util.Objects;
 
 import org.jline.reader.Buffer;
@@ -367,4 +368,9 @@ private void moveGapToCursor() {
             g1 += l;
         }
     }
+
+    @Override
+    public void zeroOut() {
+        Arrays.fill(buffer, 0);
+    }
 }

reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java

@@ -6396,4 +6396,10 @@ private void rebind(KeyMap<Binding> keyMap, String operation, String prevBinding
             keyMap.bind(ref, Character.toString(newBinding));
         }
     }
+
+    @Override
+    public void zeroOut() {
+        buf.zeroOut();
+        parsedLine = null;
+    }
 }