Fix for GetBlockValue() after block 13,440,000

Forces the block reward to zero when right shift in GetBlockValue() is
undefined, after 64 reward halvings (block height 13,440,000).
Fix importwallet nTimeFirstKey
RPC command getmininginfo showing right genproclimit
gitian: add statically built variant of bitcoind/bitcoin-cli
remove an assignment which is never used.
build: improve missing boost error reporting
doc: Add note about memory reqs for compilation
qt: Don't require db_cxx.h when wallet disabled

Fix #3978.
unified and better log/error messages for CDBEnv/CDB
[Qt] small cleanup of coincontroldialog

- use a little more Qt-style
- check for NULL pointers first and return in updateView()
- small space and formating changes
Merge pull request #3991

d34b958 [Qt] small cleanup of coincontroldialog (Philip Kaufmann)
Merge pull request #3986

65adc3a qt: Don't require db_cxx.h when wallet disabled (Wladimir J. van der Laan)
4babd08 doc: Add note about memory reqs for compilation (Wladimir J. van der Laan)
25333a2 build: improve missing boost error reporting (Wladimir J. van der Laan)
Merge pull request #3931

f61287c RPC command getmininginfo showing right genproclimit (Isidoro Ghezzi)
[Qt] rescan progress
Add gitian build guide

Work in progress...
Edit subsidy_limit_test to account for BIP42

Because no one wants 4 gold mines being discovered every mibillenium.
Have pull-tester run the listtransactions.py regression test

This should show how to run a python-based regression test
successfully in the pull-tester environment.
Merge pull request #3842 from ditto-b/master

Fix for GetBlockValue() after block 13,440,000
Merge pull request #3928

3927836 [Qt] rescan progress (Cozz Lovan)
Merge pull request #3998

cb4bdd1 Have pull-tester run the listtransactions.py regression test (Gavin Andresen)