detect_pending(true) not set in CTOR of SocketPort for UDP sockets

[Wolfgang]

Hello,

when constructing a bound TCPSocket with SocketPort,  detect_pending is set to 
true.
however, when constructing  a bound UDPSocket, it is not and therefore  
pending() is not called by the SocketService by "default". 
this could be a irritating, if one is just starting with the cc++ package.

if there is no particular reason for this, i would suggest to let the CTOR's 
behave similar. Otherwise i would suggest to add a comment about the 
differences to the documentation.

Best regards

Wolfgang