mod_h[ttp]2 v1.7.0

• rewrite of how responses and trailers are transferred between master and slave connections.
• Reduction of internal states for tasks and streams, reducing complexity for increased stability.
• Heuristic id generation for slave connections to better keep promise of connection ids unique at given point in time. This fixes problems with mod_cgid in high load situtations.
• Fix for handling of incoming trailers when no request body is sent.