Enable paranoid corruption checks in LevelDB >= 1.16
Implement SI-style (thin space) thoudands separator
Add DNS seed of open-nodes.org
[Qt] New status bar Unit Display Control and related changes.

- New status bar control shows the current Unit of Display.
  When clicked (left,or right button) it shows a context menu
  that allows the user to switch the current Unit of Display (BTC, mBTC, uBTC)
- Recent Requests and Transaction Table headers are now updated when
  unit of display is changed, because their "Amount" column now displays the
  current unit of display.
- Takes care of issue #3970 Units in transaction export csv file.
- Small refactors for reusability.
- Demo Video https://www.youtube.com/watch?v=wwcr0Yh68go&list=UUG3jF2hgofmLWP0tRPisQAQ
- changes after Diapolo's feedback. Have not been able to build after last pool, issues with boost on MacOSX, will test on Ubuntu these changes.
- removed return statement on switch
- renamed onDisplayUnitsChanged(int) to updateDisplayUnit(int)
- now getAmountColumnTitle(int unit) takes a simple unit parameter. moved to BitcoinUnits.
add OpenSSL RAND_cleanup() on OpenSSL shutdown

- to securely erase the memory used by the PNRG
- also rework 2 comments in OpenSSL init
Use async name resolving to improve net thread responsiveness

In the LookupIntern(), things changed are:

  1. Call getaddrinfo_a() instead of getaddrinfo() if available, the former is a sync version of the latter;
  2. Try using inet_pton()/inet_addr() to convert the input text to a network addr structure at first, if success the extra name resolving thread inside getaddrinfo_a() could be avoided;
  3.  An interruption point added in the waiting loop for return from getaddrinfo_a(), which completes the improve for thread responsiveness.

A easy way to see the effect is to kick off a 'bitcoind stop' immediately after 'bitcoind -daemon', before the change it would take several, or even tens of, minutes on a bad network situation to wait for the running bitcoind to exit, now it costs only seconds.

Signed-off-by: Huang Le <4tarhl@gmail.com>
secp256k1: add libtool as a dependency
secp256k1: Add build-side changes for libsecp256k1

Note: This is added to our existing automake targets rather than as a
libtool-style lib. The switch to libtool-style targets can come later if it
proves to not add any complications.
libsecp256k1 integration
Clean up release-process.md after OS X gitian changes

This is PR #4271, but with the changes to the descriptors, both the names of the
files and the names of the intermediate build artifact archives, removed.
This also closes #3775 if it goes in, because it covers the changes in
that PR.
Check signatures before respend relay

Check that all inputs are completely valid before actually
relaying a double-spend.
Fix the Qt5 build after d95ba75

Sorry, my own fault this time.
Merge pull request #4449

462ad22 Clean up release-process.md after OS X gitian changes (Micha)
Merge pull request #4312

fda3fed libsecp256k1 integration (Pieter Wuille)
5566826 secp256k1: Add build-side changes for libsecp256k1 (Cory Fields)
b150b09 secp256k1: add libtool as a dependency (Cory Fields)
qt: fix 'opens in testnet mode when presented with a BIP-72 link with no fallback'

Passes tests:

```
$ ./bitcoin-qt 'bitcoin:?r=http://www.example.com/'
.. fixed the original problem - this launches mainnet.

$ ./bitcoin-qt 'bitcoin:mngeNQbTKnmaMbx8EXCYdwUbnt9JJD52cC'
.. launches testnet

$ ./bitcoin-qt -testnet 'bitcoin:1NXXeQRyMFFFRfyUix2o7mk1vhvk2Nxp78'
.. sanity check - launches mainnet.
```

Fixes #4355. Closes #4411.
Fix formatting in release-process.md
Update Gitian Build guide to include OSX
Add support for watch-only addresses

Changes:
* Add Add/Have WatchOnly methods to CKeyStore, and implementations
  in CBasicKeyStore.
* Add similar methods to CWallet, and support entries for it in
  CWalletDB.
* Make IsMine in script/wallet return a new enum 'isminetype',
  rather than a boolean. This allows distinguishing between
  spendable and unspendable coins.
* Add a field fSpendable to COutput (GetAvailableCoins' return type).
* Mark watchonly coins in listunspent as 'watchonly': true.
* Add 'watchonly' to validateaddress, suppressing script/pubkey/...
  in this case.

Based on a patch by Eric Lombrozo.

Conflicts:
	src/qt/walletmodel.cpp
	src/rpcserver.cpp
	src/wallet.cpp
qt: Hide unspendable outputs in coin control
Watchonly balances are shown separately in gui.