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.

Rebased-From: c33b983
Avoid querying DNS seeds, if we have open connections.

The goal is to increase independence and privacy.
gitian: Bump miniupnp version to 1.9.20140701

Also change build system: STATICLIB is now MINIUPNP_STATICLIB.
ExtractAddress() -> ExtractDestination()

Fixed comments
Merge pull request #690 from whitj00/patch-3

ExtractAddress() -> ExtractDestination()
Merge pull request #674 from rnicoll/1.8.1-dev-networking

Apply network related changes from 0.9.3
Merge pull request #678 from rnicoll/1.8.1-dev-dependencies2

gitian: Bump miniupnp version to 1.9.20140701
Adding the image template for the paper wallet
Adding basic paper wallet generation with a reload button
Adding a print button, icon, and capability of printing multiple wallets per page
Adding a Compress method to the CPubKey class to mirror the Decompress method
Adding print icon to resource files.
Added public key display.
Added dropdown to print multiple paper wallets over multiple pages.
Rewired the menu button to gain access to the walletmodel object.
Fixing the variable name for amountInput
Removing debug messages and reverting a debug conditional
Added paper_wallet.png
Attempting to get print support in qt5
Adding an explicit reference to QT5's QPrinter
http://qt-project.org/wiki/Transition_from_Qt_4.x_to_Qt5
Updating QPrintPreviewDialog for qt5
Updating reference to QPrintDialog for qt5
Adding compatibility for QT4 again