Tracking issue: futures 0.3

[aturon]

This issue tracks high-level progress toward a final futures 0.3 release.

• Start the branch

0.3-alpha.1

• Work through implications of removing Error, Tracking issue: implications of removing the Error type #3
• Work through implications of pinning, Tracking issue: implications of pinning on combinators #4
• Work through implications of borrowing, Tracking issue: implications of borrowing across yield points #5

0.3-beta.1

• Task-local hooks, Add hooks sufficient to build task-local data #7
• Debugging hooks, Add debugging hooks for futures #6

0.3.0

• futures-core APIs stabilized in libcore

[jimmycuadra]

Does this change at all with the new, more conservative libs RFC?

[aturon]

Yes, updated.

[aturon]

Closing in favor of finer-grained issues.