Loggo2

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- Removed
- The remaining public data members of a Loggo object: `called`, `returned`, `returned_none` and `errored`
- Fixed
- Logging calls no longer mutate extra data

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- Changed
- Graypy dependency is not installed by default. To install with Graylog support, install with the `graylog` extra: `pip install loggo[graylog]`
- Don't allow using loggo.logme to decorate callables. Use loggo instead.
- Make Loggo.write_to_file() a private method.
- Make Loggo init param `raise_logging_errors` default to True
- Make loggo.loggo module private
- Reduce a Loggo object's public data members to minimum. Only `called`, `returned`, `returned_none` and `errored` remain public now.

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- Added
- `called`, `returned`, `returned_none` and `errored` kwargs on instantiation for custom log strings

- Changed
- do not pass a config dict on instantiation, instead just keyword arguments
- Graylog address is given to init as tuple named graylog_address instead of having the ip and port in separate arguments.
- default obscured data string `[PRIVATE_DATA] -> ********`. This string is not configurable anymore.
- default log level changed from logging.INFO to logging.DEBUG

- Removed
- loggo.events; its functionality is still available during instantiation
- line_length config, which was not respected anyway, and not really needed.
- max_dict_depth config. Now always set to the previous default value 5.
- error_level config. Now always set to the LOG_LEVEL
- Loggo.verbose contextmanager
- Loggo.log_errors contextmanager

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- Changed
- `Loggo.listen_to()` no longer takes positional argument `no_graylog_disable_log`. Instead of this, the key-value-pair `'log_if_graylog_disabled': bool` can be included in the config dict when instantiating Loggo.
- The `error_alert` kwarg of `Loggo.events()` was renamed to `error_level` and is now expected to be integer.
- The signature `Loggo.log(self, message: str, alert: Optional[str] = None, extra: Optional[Dict] = None, safe: bool = False)` is now `Loggo.log(self, level: int, msg: str, extra: Optional[Dict] = None, safe: bool = False)`.

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- Changed
- Drop support for Python versions lower than 3.6

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- Added
- Added config option: `truncation (int)`, which determines extra data value max length

- Changed
- Internals updated to allow auto-logging of static/class methods in uninstantiated classes.
- Slight reformatting of auto-generated messages (better getting of class name, no `__main__`)

- Removed
- Loggo.everything (the class decorator), now simply use Loggo