Allow -onlynet=onion to be used

Just an alias for onlynet=tor, but matches the new name
of the proxy option -onion= better.
Add IsReachable(net) function

Allows other parts of the program to query for reachable
status of a network. Similar to IsLimited(net).
Add GetNetworkName function

Returns the network name for an Network enum.
Add a way to limit deserialized string lengths

and use it for most strings being serialized.
build: Fix boost build on some platforms

When the libpath doesn't line up with the value from config.sub, we don't find
the correct path to boost's libs. This adds a hack to try another path before
giving up.

Should close #3219.
build: add option for reducing exports

Enabled automatically if boost >= 1.49.
See: https://svn.boost.org/trac/boost/ticket/2309

Also, check for a default visibility attribute, so that we can mark future
api functions correctly.
depends: fix shasum on osx < 10.9

Shasum verification from stdin doesn't work there, so we write to a file
instead.

Formatted a bit too.
build: add funcs.mk to the list of meta-depends

If anything in funcs.mk changes, everything must rebuild
Changed LevelDB cursors to use scoped pointers to ensure destruction when going out of scope.

This corrects a bug where an exception thrown reading from the database causes the cursor to
be left open, which causes an assertion error to occur when the database is deleted (around
line 938 of init.cpp).
Merge pull request #4663

4975ae1 build: add option for reducing exports (Cory Fields)
devtools: Exclude default exports from symbol-checker script

See discussion in #4663.
Merge pull request #4656

5cbda4f Changed LevelDB cursors to use scoped pointers to ensure destruction when going out of scope. (Ross Nicoll)
build: Add --with-utils (bitcoin-cli and bitcoin-tx, default=yes).
Help string consistency tweaks. Target sanity check fix.
Merge pull request #4711

c101c76 build: Add --with-utils (bitcoin-cli and bitcoin-tx, default=yes). Help string consistency tweaks. Target sanity check fix. (randy-waterhouse)
Merge pull request #4709

e42363d build: add funcs.mk to the list of meta-depends (Cory Fields)
1910910 depends: fix shasum on osx < 10.9 (Cory Fields)
Merge pull request #4655

216e9a4 Add a way to limit deserialized string lengths (Pieter Wuille)
doc: Remove outdated information about boost versions

Bitcoin core should work with any remotely recent boost version
if a proper build environment is present. Remove a confusing comment
from the build documentation.
Add detailed network info to getnetworkinfo RPC

This commit adds per-network information to the
getnetworkinfo RPC call:

- Is the network limited?
- Is the network reachable
- Which proxy is used for this network, if any

Inspired by #2575.
Merge pull request #4605

aa82795 Add detailed network info to getnetworkinfo RPC (Wladimir J. van der Laan)
075cf49 Add GetNetworkName function (Wladimir J. van der Laan)
c91a947 Add IsReachable(net) function (Wladimir J. van der Laan)
60dc8e4 Allow -onlynet=onion to be used (Wladimir J. van der Laan)
qt: Use quint64 for formatServicesStr

`uint64_t` was causing a build error on some systems, as that type is
not known after including just the Qt headers.