client: allow connecting to IPv6 addresses in default initializer.
collection: rename delete() to remove() and deprecate delete.

All of the other drivers have standardized on remove for the name for
this operation. We should go ahead and do the same.
flags: add mongoc_remove_flags_t for naming uniformity.
doc: add new topic based help.

This uses mallard for topic based help as well as functional documentation
(API Reference). It includes inline examples, clean HTML formatting, and
manpage generation (this could still use a little incremental work though).

Automake fixes for installing manpages will be in a followup patch.
doc: start on bulk operations doc.
client-pool: add mongoc_client_pool_set_ssl_opts().

This allows setting the default ssl opts for a client pool. All created
clients will share this setting.
doc: bail on systems without support to generate man pages.
tests: use proper flags for removal.
tests: disable deprecation support for clang.
build: update ax_pthread for some clang fixes.
build: bump libbson for various fixes.
build: add mongoc_client_pool_set_ssl_opts() to ABI.
client-pool: only set SSL opts if we are compiling with SSL support.
database: use mongoc_remove_flags_t.
doc: only install man pages if automake conditional is set.
tools: suprcess zealous clang cast align warning.

These are checked in various other places for correctness. Silence the
clang warning which can't detect that this is the case.

Also add an assertion just to be safe :)
Revert "Be gentle to user provided BSON include path and only modify if really"

This reverts commit 9ac0eb0f6850ad4aefc4043d19aea4fe70e6817f.

This was breaking the default CMake build on Windows.
build: bump libbson for test fix.
test: only do IPv6 check if MONGOC_CHECK_IPV6 is set.
tests: allow port to be in MONGOC_TEST_HOST.