Update Qt 4.8.3 download link

Conflicts:
	contrib/gitian-descriptors/README
Merge commit 'efde29e' into HEAD
Fix and improve release-process.md

This commit adds a step, which is to git checkout the version to be
built. This ensures that the gitian-descriptors for said version will be
the correct ones. In addition, it updates the links for several
dependencies, where the previously existing links were dead.

Conflicts:
	doc/release-process.md
Merge commit '71888bf' into HEAD

Conflicts:
	src/netbase.h
Update contrib/debian: proper desktop category and update changelog
Merge commit '3f8241c' into HEAD
Avoid core dump if rpc port is in use.

The cleanup code needs to check for NULL rpcworkers thread group.
Update michagogo's gitian pgp key, adding UIDs
Bugfix: Avoid trying to parse outputs that aren't relevant to CWalletTx::GetAmounts

This fixes a warning when an output we aren't concerned with can't be parsed.
Bugfix: Supress "address" key in transaction details, when the destination isn't recognized

Previously, it would pass corrupt/random through base58.
RPC: prevent crash with walletpassphrase

- fix crash with walletpassphrase by checking if RPC server is running and
  give a friendly error message how to fix this (fixes #3100)
- add 3 new RPCErrorCodes RPC_SERVER_NOT_STARTED
- use the new code where needed / missing

Upstream: 4315ec1a722a290ba2bb2b86080a787f6174e2a2

Conflicts:
	src/rpcnet.cpp
	src/rpcwallet.cpp
bitcoingui: show main window (if hidden) on modal messages

Conflicts:
	src/qt/bitcoingui.cpp
Merge commit 'b56b102' into HEAD
Merge commit '5d37b9d' into HEAD

Conflicts:
	main.h
qt: add license header to source files

Closes #839

Conflicts:
	src/qt/addressbookpage.cpp
	src/qt/guiutil.cpp
	src/qt/intro.cpp
	src/qt/intro.h
	src/qt/macnotificationhandler.h
	src/qt/optionsdialog.cpp
	src/qt/optionsmodel.cpp
	src/qt/paymentrequestplus.cpp
	src/qt/paymentrequestplus.h
	src/qt/paymentserver.cpp
	src/qt/receivecoinsdialog.cpp
	src/qt/receivecoinsdialog.h
	src/qt/receiverequestdialog.cpp
	src/qt/receiverequestdialog.h
	src/qt/trafficgraphwidget.cpp
	src/qt/trafficgraphwidget.h
	src/qt/walletmodeltransaction.cpp
	src/qt/walletmodeltransaction.h
Merge commit '51e3e09' into HEAD

Conflicts:
	build-msw.txt
Add additional data update to release-process.md

This adds https://github.com/bitcoin/bitcoin.org/pull/270 to the to-do
list for each release, avoiding future situations like
https://bitcointalk.org/index.php?topic=336042.0.
Partial: Sanitize assert usage and refuse to compile with NDEBUG.

There were quite a few places where assert() was used with side effects,
 making operation with NDEBUG non-functional.  This commit fixes all the
 cases I know about, but also adds an  #error on NDEBUG because the code
 is untested without assertions and may still have vulnerabilities if
 used without assert.

Conflicts:
	src/key.cpp
	src/main.cpp
	src/wallet.cpp
Change release-process.md to sign release tags

Conflicts:
	doc/release-process.md
Update build-osx.md