Add waitForChildren command

Author: James Hagborg

src/main/java/org/usfirst/frc/team69/util/CommandBuilder.java

@@ -10,6 +10,7 @@
 import edu.wpi.first.wpilibj.command.InstantCommand;
 import edu.wpi.first.wpilibj.command.Subsystem;
 import edu.wpi.first.wpilibj.command.WaitCommand;
+import edu.wpi.first.wpilibj.command.WaitForChildren;
 import edu.wpi.first.wpilibj.command.WaitUntilCommand;
 
 /**
@@ -201,6 +202,17 @@ public CommandBuilder releaseAll() {
         return this;
     }
 
+    /**
+     * Wait for all running parallel commands to finish before executing the
+     * next command.
+     * 
+     * @return This CommandBuilder object
+     */
+    public CommandBuilder waitForChildren() {
+        m_cmdGroup.addSequential(new WaitForChildren());
+        return this;
+    }
+    
     /**
      * Build a command.  Note that for simplicity, calling this method 
      * multiple times will return the same {@link Command} object.  This