Revert "Clean up sharding-related code"

This reverts commit bb2bebf9feb11f8b241696c9d96856fbc5fbe9fe.
Revert "Encapsulate cyclic in an opaque struct"

This reverts commit 59c93c6ce541a432d29c71091e4ea884cea37e36.

Conflicts:
	src/cyclic.c
Revert "Calculate shard begin and end"

This reverts commit 4bb4ad9125b4f1f7147d58edb5a0a774771ad3df.

Conflicts:
	src/zopt.ggo