New serial log at ~/.octoprint/logs/serial.log

Logs the same content as the terminal tab and is restricted to 2MB in size (hopefully).

Closes #77

octoprint/server.py

@@ -509,11 +509,20 @@ class Server():
 					"when": "D",
 					"backupCount": "1",
 					"filename": os.path.join(settings().getBaseFolder("logs"), "octoprint.log")
+				},
+				"serialFile": {
+					"class": "logging.handlers.RotatingFileHandler",
+					"level": "DEBUG",
+					"formatter": "simple",
+					"maxBytes": 2 * 1024 * 1024, # let's limit the serial log to 2MB in size
+					"filename": os.path.join(settings().getBaseFolder("logs"), "serial.log")
 				}
 			},
 			"loggers": {
-				"octoprint.gcodefiles": {
+				"SERIAL": {
-					"level": "DEBUG"
+					"level": "DEBUG",
+					"handlers": ["serialFile"],
+					"propagate": False
 				}
 			},
 			"root": {

octoprint/util/comm.py

@@ -9,6 +9,7 @@ import re
 import traceback
 import threading
 import Queue as queue
+import logging
 
 import serial
 
@@ -143,6 +144,9 @@ class MachineCom(object):
 	STATE_CLOSED_WITH_ERROR = 10
 	
 	def __init__(self, port = None, baudrate = None, callbackObject = None):
+		self._logger = logging.getLogger(__name__)
+		self._serialLogger = logging.getLogger("SERIAL")
+
 		if port == None:
 			port = settings().get(["serial", "port"])
 		if baudrate == None:
@@ -422,6 +426,7 @@ class MachineCom(object):
 	
 	def _log(self, message):
 		self._callback.mcLog(message)
+		self._serialLogger.debug(message)
 		try:
 			self._logQueue.put(message, False)
 		except: