Libbson 0.98.0

One more step closer to a 1.0!

This release has a few fixes as we near the finish line of a 1.0 release.
We have bumped the version to 0.98.0 to sync up with MongoDB C driver, which
is the primary consumer of this library.

This release includes a new memory callback vtable to help in embedding
situations that have their own custom allocator such as various language
runtimes.

A few compilation fixes for various C++ compilers have also been included.

A special thanks to:

• Itay Neeman
• Michael Whittaker

Happy Hacking!

-- Christian