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
gitian: add statically built variant of bitcoind/bitcoin-cli
remove an assignment which is never used.
unified and better log/error messages for CDBEnv/CDB
Add gitian build guide

Work in progress...
Merge pull request #3994

2c47a00 Add gitian build guide (Wladimir J. van der Laan)
Merge pull request #3572

f7257cf unified and better log/error messages for CDBEnv/CDB (Philip Kaufmann)
Update README.md
Merge pull request #4005 from Telepatheic/patch-1

Update README.md
Added instructions for when wrong openssl detected after brew link
Move assert(pindexNew); to above where we dereference pindexNew.
Merge pull request #4010

94c8bfb Move assert(pindexNew); to above where we dereference pindexNew. (Gregory Maxwell)
Merge pull request #3972

fbf617a remove an assignment which is never used. (Yoichi Hirai)
Doxygen-compatible comments in coding style
Show error message if ReadConfigFile fails

A runaway exception was raised if ReadConfigFile fails (usually
due to a parse error in bitcoin.conf). Show an error message instead.

Fixes #4013.
build: Sync ax_boost_base.m4 with upstream.

This should fix 32bit boost detection on Ubuntu Saucy+. Fixes #3945.