Stricter handling of orphan transactions

Prevent denial-of-service attacks by banning
peers that send us invalid orphan transactions
and only storing orphan transactions given to
us by a peer while the peer is connected.

Rebased-From: c74332c67806ed92e6e18de174671a7c30608780

Conflicts:
	src/main.cpp
Merge pull request #721 from rnicoll/1.8.1-dev-orphan

Stricter handling of orphan transactions
Switched to older QT API calls to that paper wallet printing is compatible with Qt 4.6.4.
When printing paper wallets, add a warning message about security if connected to any peers.
Regenerate addresses at the end of the loop so that the shown wallet is the first to print.
Elaborating on the message after paper wallets are printed about ensuring print quality.
Update bootstrap mirrors
Merge pull request #725 from rnicoll/1.8.1-dev-qt4

Fix paper wallet compatibility with Gitian
Merge pull request #730 from patricklodder/1.8.1-dev-bootstrap-mirrors

Update bootstrap mirrors
Merge pull request #726 from Andymeows/1.8.1-dev

Add a warning message about printing paper wallets while online
Correct example for IP mask passed to rpcallowip.
Merged in pink changes from 1.7.2