Don't poll showmyip.com, it doesn't exist anymore
Don't poll showmyip.com, it doesn't exist anymore

Fixes #4679.

This leaves us with only one candidate, checkip.dyndns.org.
GetMyExternalIP should be phased out as soon as possible.

Conflicts:
	src/net.cpp

munnecoin/Munnewallet,munnecoin/Munnewallet,munnecoin/Munnewallet,munnecoin/Munnewallet,munnecoin/Munnewallet,munnecoin/Munnewallet,munnecoin/Munnewallet,munnecoin/Munnewallet