Use the logging module directly instead of home-grown code.

This has the advantage of overall less custom code; as well as support
for per-module configuration. This would enable a potential solution for
ultrabug#1479, since in the future
it can allow per-module configuration of log levels.

I expect this to mainly help module creators, allowing them to enable
logging for only their module, while disabling all other messages. It
also is easier to use, since the `logging` module's interface is
generally simpler than `self.py3`.

Here, I've made the decision to keep the message format as close as
possible to the existing log messages.

py3status/core.py

@@ -1,6 +1,5 @@
 import logging
 import logging.handlers
-import logging.config
 import sys
 import time
 from collections import deque
@@ -32,6 +31,12 @@
 }
 
 
+LOGGING_LEVELS = {
+        "error": logging.ERROR,
+        "warning": logging.WARNING,
+        "info": logging.INFO,
+}
+
 DBUS_LEVELS = {"error": "critical", "warning": "normal", "info": "low"}
 
 CONFIG_SPECIAL_SECTIONS = [
@@ -531,9 +536,35 @@ def load_modules(self, modules_list, user_modules):
                 msg = f'Loading module "{module}" failed ({err}).'
                 self.report_exception(msg, level="warning")
 
+    def _setup_logging(self):
+        """Set up the global logger."""
+        root = logging.getLogger(name=None)
+        if self.config.get("debug"):
+            root.setLevel(logging.DEBUG)
+        else:
+            root.setLevel(logging.DEBUG)
+
+        log_file = self.config.get("log_file")
+        if log_file:
+            handler = logging.FileHandler(log_file, encoding='utf8')
+        else:
+            logging.handlers.SysLogHandler()
+        handler.setFormatter(logging.Formatter(
+                fmt='%(asctime)s %(levelname)s %(module)s %(message)s',
+                datefmt='%Y-%m-%d %H:%M:%S',
+                style='%'))
+        root.addHandler(handler)
+
+    def setup(self):
+        """
+        Setup py3status and spawn i3status/events/modules threads.
+        """
+        self._setup_logging()
+
     def _log_gitversion(self):
         # A git repo is detected looking for the .git directory
 
+
         git_path = Path(__file__).resolve().parent.parent / ".git"
         if not git_path.exists():
             return