v1.0.0

• BREAKING: session.close() is introduced, and must be called when a session is no longer needed, otherwise the program will not terminate.
• Use new-style cookie-based authentication when available, instead of old X-Okapi-Token authentication, refreshing the token after half of its TTL has elapsed.
• Add logging category for authentication/reauthentication.
• Internally, use an HTTPError exception class.