Create standalone C++ lib for gzip compression #10

The zlib/gzip compression headers of mapnik-vt, if extracted, would be useful a number of places immediately:

• To immediately start sharing code between mapnik-vt/node-mapnik and tippecanoe (also the shaver and china-cutout)
• To be available to other libraries like https://github.com/mapbox/vector-tile

TODO:

• New repo called mapbox/gzip-cpp
• Make able to be used header only, or as a compiled lib (by using _impl.hpp design per Make it possible to use as header only library geojson-cpp#24
• Package in mason
• Re-integrate back into mapnik-vt as a new dependency
• Formalize document on how _impl.hpp headers work in /cpp docs. - started at Documentation on when/why/how to write _impl.hpp #12

Sources to pull from include: https://github.com/mapbox/mapnik-vector-tile/blob/master/src/vector_tile_compression.hpp and https://github.com/mapbox/mapnik-vector-tile/blob/master/src/vector_tile_compression.ipp. (NOTE: The ipp file is == to _impl.hpp)

Extras ideas:

• Could leverage https://github.com/madler/zlib/blob/2fa463bacfff79181df1a5270fb67cc679a53e71/uncompr.c

/cc @GretaCB @mapsam