2.5.0

• Add rename_table() and rename_multimap_table()
• Add Key and Value implementations for the unary tuple type (i.e. (T,))
• Fix an issue which could cause a panic when concurrently performing read and write transactions,
  when debug_assertions were enabled
• Optimize retain() and retain_in() to use less space in the database file
• Improve handling of some internal errors to return LockPoisoned instead of panicking