Updated comment for Channel and TcpChannel constructors (to prevent issues like #154)

include/channel.h

@@ -29,6 +29,10 @@ private:
 public:
     /**
      *  Construct a channel object
+     * 
+     *  The passed in connection pointer must remain valid for the 
+     *  lifetime of the channel.
+     * 
      *  @param  connection
      */
     Channel(Connection *connection) : _implementation(new ChannelImpl()) 

include/tcpchannel.h

@@ -4,7 +4,7 @@
  *  Extended channel that can be constructed on top of a TCP connection
  *
  *  @author Emiel Bruijntjes <emiel.bruijntjes@copernica.com>
- *  @copyright 2015 Copernica BV
+ *  @copyright 2015 - 2017 Copernica BV
  */
 
 /**
@@ -25,6 +25,10 @@ class TcpChannel : public Channel
 public:
     /**
      *  Constructor
+     * 
+     *  The passed in connection pointer must remain valid for the 
+     *  lifetime of the channel.
+     * 
      *  @param  connection
      */
     TcpChannel(TcpConnection *connection) :