Write fee estimate and peers files only when initialized

Fixes #4669.

Move the loading of addresses to StartNode() to make it more
self-contained.
[Wallet] Watch-only fixes
build: fix dynamic boost check when --with-boost= is used
build: fix qt test build when libprotobuf is in a non-standard path
rpc-tests: don't spew non-errors to stdout

There's a brief race here, the process might've already exited and cleaned up
after itself. If that's the case, reading from the pidfile will harmlessly
fail. Keep those quiet.
Merge pull request #5073

d5fd094 build: fix qt test build when libprotobuf is in a non-standard path (Cory Fields)
a7d1f03 build: fix dynamic boost check when --with-boost= is used (Cory Fields)
Merge pull request #4937

ccca27a [Wallet] Watch-only fixes (Cozz Lovan)
Typo in test
Merge pull request #5080

e21b2e0 Typo in test (Luke)
Merge pull request #5074

005b5af rpc-tests: don't spew non-errors to stdout (Cory Fields)
Merge pull request #4942

9406471 Write fee estimate and peers files only when initialized (Wladimir J. van der Laan)
boost: drop dependency on is_fundamental in serialization

There's only one case where a vector containing a fundamental type is
serialized all-at-once, unsigned char. Anything else would lead to
strange results.

Use a dummy argument to overload in that case.
boost: drop dependency on tuple in serialization

There's only one user of this form of serialization, so it can be easily
dropped. It could be re-added if desired when we switch to c++11.
boost: remove CPrivKey dependency from CECKey

This allows CECKey to be used without directly depending on the secure
allocators
boost: drop boost dependency in core.cpp
boost: drop boost dependency in utilstrencodings.cpp
boost: drop boost dependency in version.cpp.

Also add a test to verify.
Merge pull request #5082

5f4bcf6 boost: drop boost dependency in version.cpp. (Cory Fields)
352058e boost: drop boost dependency in utilstrencodings.cpp (Cory Fields)
e1c9467 boost: drop boost dependency in core.cpp (Cory Fields)
e405aa4 boost: remove CPrivKey dependency from CECKey (Cory Fields)
5295506 boost: drop dependency on tuple in serialization (Cory Fields)
1d9b86d boost: drop dependency on is_fundamental in serialization (Cory Fields)
txoutsbyaddress index