Fix: Use Exception, not BaseException

Custom exception should be derived from Exception, not BaseException.

Not only is this specified in the python documentation, but also
tornado will be able to handle Exceptions in requests perfectly fine
and return an HTTP 500 for them, but crash hard (as in, server shut
down follows) for BaseExceptions.

src/octoprint/plugin/core.py

@@ -1213,15 +1213,15 @@ class Plugin(object):
 class RestartNeedingPlugin(Plugin):
 	pass
 
-class PluginNeedsRestart(BaseException):
+class PluginNeedsRestart(Exception):
 	def __init__(self, name):
-		BaseException.__init__(self)
+		Exception.__init__(self)
 		self.name = name
 		self.message = "Plugin {name} cannot be enabled or disabled after system startup".format(**locals())
 
-class PluginLifecycleException(BaseException):
+class PluginLifecycleException(Exception):
 	def __init__(self, name, reason, message):
-		BaseException.__init__(self)
+		Exception.__init__(self)
 		self.name = name
 		self.reason = reason
 

src/octoprint/printer/__init__.py

@@ -467,6 +467,6 @@ class PrinterCallback(object):
 		"""
 		pass
 
-class UnknownScript(BaseException):
+class UnknownScript(Exception):
 	def __init__(self, name, *args, **kwargs):
 		self.name = name

src/octoprint/server/api/languages.py

@@ -143,5 +143,5 @@ def _validate_archive_name(name):
 		raise InvalidLanguagePack("Provided language pack contains invalid name {name}".format(**locals()))
 
 
-class InvalidLanguagePack(BaseException):
+class InvalidLanguagePack(Exception):
 	pass

src/octoprint/slicing/exceptions.py

@@ -33,7 +33,7 @@ __license__ = 'GNU Affero General Public License http://www.gnu.org/licenses/agp
 __copyright__ = "Copyright (C) 2015 The OctoPrint Project - Released under terms of the AGPLv3 License"
 
 
-class SlicingException(BaseException):
+class SlicingException(Exception):
 	"""
 	Base exception of all slicing related exceptions.
 	"""
@@ -73,7 +73,7 @@ class UnknownSlicer(SlicerException):
 		SlicerException.__init__(self, slicer, *args, **kwargs)
 		self.message = "No such slicer: {slicer}".format(slicer=slicer)
 
-class ProfileException(BaseException):
+class ProfileException(Exception):
 	"""
 	Base exception of all slicing profile related exceptions.
 
@@ -86,7 +86,7 @@ class ProfileException(BaseException):
 	   Identifier of the profile for which the exception was raised.
 	"""
 	def __init__(self, slicer, profile, *args, **kwargs):
-		BaseException.__init__(self, *args, **kwargs)
+		Exception.__init__(self, *args, **kwargs)
 		self.slicer = slicer
 		self.profile = profile
 

src/octoprint/util/comm.py

@@ -1982,9 +1982,9 @@ class TypedQueue(queue.Queue):
 		return item
 
 
-class TypeAlreadyInQueue(BaseException):
+class TypeAlreadyInQueue(Exception):
 	def __init__(self, t, *args, **kwargs):
-		BaseException.__init__(self, *args, **kwargs)
+		Exception.__init__(self, *args, **kwargs)
 		self.type = t