AddToWallet implies BindWallet

Now that AddToWallet is called when loading transactions from the
wallet database, BindWallet can be integrated into that and does not
need to be an extra step.

Leaves behaviour unchanged, but makes the
fFromLoadWallet/!fFromLoadWallet paths in AddToWallet a bit more
symmetric.
Also switch the (unused) verification code to low-s instead of even-s.

a81cd968 introduced a malleability breaker for signatures
(using an even value for S). In e0e14e43 this was changed to
the lower of two potential values, rather than the even one.
Only the signing code was changed though, the (for now unused)
verification code wasn't adapted.
Fix script test handling of empty scripts

Previously an empty script would evaluate to OP_0
Test CHECKMULTISIG with m == 0 and n == 0
Fix bloom filter not to use bit_mask
Added instructions for when wrong openssl detected after brew link
Doxygen-compatible comments in coding style
Bugfix: configure: Look in libx32 subdirectory for boost libraries
Changed bitrpc.py's raw_input to getpass for passwords to conceal characters during command line input. Getpass is in Python stdlib so no additional dependencies required.
Prevent socket leak in ThreadSocketHandler.

When we are over our outbound limit ThreadSocketHandler would try to
 keep the connection if the peer was addnoded.

This didn't actually work for two reasons: It didn't actually run
 the accept code due to mistaken code flow, and because we have a
 limited number of outbound semaphores it couldn't actually use the
 connection.

Instead it leaked the socket, which might have caused issue #4034.

This patch just takes out the non-functioning white-listing for now.
Correct some proxy related socket leaks.
build: add glibc/libstdc++ back-compat stubs

glibc/libstdc++ have added new symbols in later releases. When running a new
binary against an older glibc, the run-time linker is unable to resolve the
new symbols and the binary refuses to run.

This can be fixed by adding our own versions of those functions, so that the
build-time linker does not emit undefined symbols for them.

This enables our binary releases to work on older Linux distros, while not
incurring the downsides of a fully static binary.
build: add an option for enabling glibc back-compat

Using "./configure --enable-glibc-back-compat" will attempt to be
compatible with a target running glibc abi 2.9 and libstdc++ abi 3.4.
gitian-linux: --enable-glibc-back-compat
Merge pull request #4016

8414cb0 Doxygen-compatible comments in coding style (Wladimir J. van der Laan)
doc: add note about translations to README.md
Merge pull request #4041

1528397 doc: add note about translations to README.md (Wladimir J. van der Laan)
Merge pull request #4009

7328898 Added instructions for when wrong openssl detected after brew link (olalonde)
Merge pull request #3912

b1b9c76 Fix bloom filter not to use bit_mask (peryaudo)
build: add symbol for upcoming gcc 4.9's libstdc++