Remove dummy PRIszX macros for formatting

Size specifiers are no longer needed now that we use typesafe tinyformat
for string formatting, instead of the system's sprintf.

No functional changes.

This continues the work in #3735.
Reduce bignum.h now it is only needed for scriptnum_tests
Move bignum.h to test/
Squashed 'src/leveldb/' changes from 9094c7f..7924331

42dcc7e Merge upstream LevelDB 1.17.
e353fbc Release LevelDB 1.17
269fc6c Release LevelDB 1.16
REVERT: 9094c7f Temporarily revert to writing .sst files instead of .ldb

git-subtree-dir: src/leveldb
git-subtree-split: 79243314e40ac31d79c68e5658a1d6a64800d50b
Merge src/leveldb changes for LevelDB 1.17.
Fix addnode "onetry": Connect with OpenNetworkConnection
Move base58.h implementation code to base58.cpp
Merge pull request #4160

7cd0af7 Move bignum.h to test/ (Pieter Wuille)
ccc84e0 Reduce bignum.h now it is only needed for scriptnum_tests (Pieter Wuille)
ProcessGetData(): abort if a block file is missing from disk
Switch stdout to line buffering

Use line buffering (instead of block buffering) so that messages arrive
immediately in systemd-journald, tail -f debug.log, and the like.
Merge pull request #4175

283e405 Switch stdout to line buffering (shshshsh)
rpc: pass errors from async_accept

According to the [boost::asio documentation](http://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio/reference/basic_socket_acceptor/async_accept/overload2.html),
the function signature of the handler must be:

    void handler(
      const boost::system::error_code& error // Result of operation.
    );

We were binding *all* the arguments, instead of all but the error,
resulting in nullary function that never got the error. Fix this
by adding an input argument substitution.
rpc: Make sure conn object is always cleaned up

Make sure conn object always gets cleaned up by using a
`boost::shared_ptr`.

This makes valgrind happy - before this commit, one connection object
always leaked at shutdown, as well as can avoid other leaks, when
for example an exception happens.

Also add an explicit Close() to the !ClientAllowed path to make it similar
to the normal path (I'm not sure whether it is needed, but it
can't hurt).
doc: remove mention of `-rpctimeout` from man page

That option hasn't existed for a long time.
rpc: keep track of acceptors, and cancel them in StopRPCThreads

Fixes #4156.

The problem is that the boost::asio::io_service destructor
waits for the acceptors to finish (on windows, and boost 1.55).

Fix this by keeping track of the acceptors and cancelling them before
stopping the event loops.
Merge pull request #4161

938b689 Squashed 'src/leveldb/' changes from 9094c7f..7924331 (Pieter Wuille)
Add CODESEPARATOR/FindAndDelete() tests
Merge pull request #4165

f6b7c64 Move base58.h implementation code to base58.cpp (Pieter Wuille)
Merge pull request #4138

783b182 Remove dummy PRIszX macros for formatting (Wladimir J. van der Laan)
LoadBlockIndexDB(): Require block db reindex if any blk*.dat files are missing.