Stop configuring the root logger on import

logging.basicConfig() at import time in __init__.py silently clobbered the
embedding application's own logging setup. Replace it with a NullHandler so
the library stays silent by default without touching global config.

Also stop MeshCore.__init__ from unconditionally forcing the "meshcore"
logger to INFO when neither debug= nor only_error= is passed - only set a
level when the caller explicitly asks for one, otherwise leave whatever the
app already configured alone.

Document the idiomatic logging setup for consumers in README.md.

Fixes #58

README.md

@@ -371,6 +371,15 @@ meshcore = await MeshCore.create_serial("/dev/ttyUSB0", debug=True)
 
 This logs detailed information about commands sent and events received.
 
+meshcore_py does not configure Python's root logger or call `logging.basicConfig()` itself - it only attaches a `NullHandler` so it stays silent by default. To see its logs, configure logging in your own application, e.g.:
+
+```python
+import logging
+
+logging.basicConfig(level=logging.INFO)
+logging.getLogger("meshcore").setLevel(logging.DEBUG)
+```
+
 ## Common Examples
 
 ### Sending Messages to Contacts

src/meshcore/__init__.py

@@ -9,9 +9,11 @@ from .packets import BinaryReqType
 from .serial_cx import SerialConnection
 from .tcp_cx import TCPConnection
 
-# Setup default logger
-logging.basicConfig(level=logging.INFO)
+# Setup default logger. Libraries must not configure the root logger (that's
+# the embedding application's call) - a NullHandler just silences the "no
+# handlers found" warning when the app hasn't configured logging at all.
 logger = logging.getLogger(__name__)
+logger.addHandler(logging.NullHandler())
 
 __all__ = [
     "BinaryReqType",

src/meshcore/meshcore.py

@@ -46,13 +46,13 @@ class MeshCore:
         self.commands = CommandHandler(default_timeout=default_timeout)
         self.commands.set_contact_getter_by_prefix(self.get_contact_by_key_prefix)
 
-        # Set up logger
+        # Set up logger. Only override the level when the caller explicitly
+        # asked for debug/only_error behavior - otherwise leave whatever
+        # level the embedding app already configured alone.
         if debug:
             logger.setLevel(logging.DEBUG)
         elif only_error:
             logger.setLevel(logging.ERROR)
-        else:
-            logger.setLevel(logging.INFO)
 
         # Set up connections
         self.commands.set_connection(self.connection_manager)