compat: whitespace.
check_docs
fixed docs to align with headers
reader: add bson_reader_new_from_fd() convenience API.
yajl: use int64_t from bson instead of C99 long long.
reader: update in code docs for reader
build: move m4 to build/m4.
string: add docs.
clock: fix includes on osx 10.6.8.
build: use libtool from variable.
tests: use _SC_PHYS_PAGES when available.
build: track if we have stdbool.h at configure time.

This adds BSON_HAVE_STDBOOL_H to bson-config.h so that we can easily
include <stdbool.h> when available. The previous check was not ever
getting used by external software because they would also have to
define HAVE_STDBOOL_H, which nobody does. And of course, this causes
inconsistencies in function calls.
README: Add some build dependency information.
README: cleanup deps.
README: update win32 build.
memory: memalign is not used in the mongo-c-driver or libbson.

So lets remove it, we don't want to maintain unnecessary stuff.
README: add pkg-config to freebsd and smartos.

Not strictly required for libbson itself, but helps when people go
to build mongo-c-driver since it relies on it to find libbson-1.0.pc
build: check for snprintf during config for mingw cross compiles.
tests: check HAVE_SNPRINTF before defining.
ABI: remove bson_memalign0() from ABI.