Tracking issue for log evaluation

[alexcrichton]

This is the tracking issue for the evaluation performed by the libs team this week:

• #[macro_use(info)] raise error: macro undefined: 'log!'
• Link to logging sinks other than env_logger in the README/crate docs
• Support construction of LogRecords and LogMetadata
• Remove logger shutdown
• Implement Debug for LogMetadata, LogRecord
• FromStr impls for LogLevel, LogLevelFilter use () as error type
• Use env_logger instead of my_logger in doc example
• Crate docs should mention the logging levels and corresponding macros
• Add example for log! macro
• Document max_level_*, release_max_level_* features in crate docs
• Add examples to debug!, error!, info!, trace!, warn!
• Expand log! docs for max_level_*
• Add example for second log_enabled! pattern variant
• LogLocation doc improvements
• LogMetadata doc improvements
• LogRecord doc improvements
• SetLoggerError doc improvements
• ShutdownLoggerError doc improvements
• LogLevel doc improvements
• LogLevelFilter doc improvements
• max_log_level doc improvements
• set_logger doc improvements
• set_logger_raw doc improvements
• Linkify crate doc description
• Add CI badges to Cargo.toml
• Update Cargo.toml documentation link to docs.rs
• Add keywords to Cargo.toml
• Change html_root_url to https://docs.rs/$crate/$version
• Reduce "stuttering" in types
• Add serde impls for LogLevel/LogLevelFilter
• Implement common traits for more types
• Remove env_logger from this repository
• Change set_logger to panic on error
• Consider changing the default enabled log levels
• Ensure 0.3 works with the next major release
• Structured Logging

• Standardize on capitalization of log levels

• Bump version to 1.0 (after all else)

[dtolnay]

Closing because this is no longer useful as a tracking issue -- the only remaining item is structured logging which is being tracked in #149. If anyone would like to raise an additional 1.0 blocker, please open a new issue for it.