Buffered pipeline tail capacity fix

Fixes the missing buffer capacity for the tail channel

Fluent API and Simpler multiplexing using Junctions

Routing is much easier and fluent via Junctions API
See examples for how to use Junctions.

v1.0.0 Gopipe release

Adding Semver2.0.0 compliant tags to support a v2 merge.

• v2 adds a simpler API including easy Junction creation (ChanFans in v1).
• Enqueue and Dequeue style pipeline control.