Strata v2.0.0-alpha.80

• Implement reusable serializer.
• Destructible.rescue() is now dubious.
• Use Operation only for file system operations.
• Upgrade writeahead to 0.0.12.
• Upgrade operation to 6.0.0-alpha.4.
• Upgrade fracture to 0.3.0-alpha.32.
• Upgrade turnstile to 6.0.0-alpha.52.
• Use Operation for all file system operations.
• Use Operation file system readers.
• Fix write-ahead split, new write-ahead serializer.
• Storage generates same page id.
• Fix key and right vivification.

Closes #749.