SwiftNIO HTTP/2 0.2.0

Semver Major

• Changed around the types used on HTTP2Frame. (#16)
• Formally required Swift 4.1, though Swift 4.0 never worked with this repo. (#21)

Semver Minor

• Added support for newish nghttp2 versions. (#23)
• Added support for old nghttp2 versions. (#29)

Semver Patch

• Laid some groundwork for pure-Swift implementation. (#10, #14)
• Fixed issue where child channels would not be correctly activated. (#27)
• Fixed issue where trailers would fail to be sent. (#25)
• Prevented crashes when the client preamble was invalid. (#12)
• Prevented crashes when SETTINGS_MAX_CONCURRENT_STREAMS was set to be higher than the cache of old streams. (#13)
• Prevented crashes due to discarding active streams instead of invalid ones. (#11)
• Cleaned up submodule checkout. (#20)
• Documentation improvements. (#18)
• Many test improvements (#8, #9, #15)