v1.1.0

Mainly some fixes for PSR-3 compliance, some of which will cause exceptions to be thrown where they weren't before in invalid conditions. Specifically, logging an invalid $level value will now throw a Psr\Log\InvalidArgumentException.

• Add PSR-3-required handling of 'exception' key in context.
• Add PSR-3-required {interpolation} in log messages.
• Various documentation and typehint improvements.
• Eliminated a duplicate variable in StringTransaction.
• Make sure an invalid $level passed to log() throws an exception. (Except for BufferedLogger/ChainLogger.)
• Fix formatting of bools and null during string conversion.
• Consistently throw Psr\Log\InvalidArgumentException not \InvalidArgumentException.
• Clean up duplicate code in AbstractLogger. Duplicate methods are now deprecated, will be removed in 2.0.
• Updated static analysis configurations.
• Remove (harmless) duplicate trait use.
• Make sure Node::level() always returns a string.
• Allow telemetry nodes to have or inherit log levels. (This allows treating telemetry as being of the same severity of the most severe event it captured.)
• Add LogLevels::isValid().
• Add LevelInterface and LogEntryInterface.