Remove obsolete imports and code

- landscape.io pointed out obsolete imports
- there is also an obsolete variable and lock in throttle.py
- add Exception type to BMConfigParser().save

src/configparser.py

@@ -56,7 +56,7 @@ class BMConfigParser(ConfigParser.SafeConfigParser):
             shutil.copyfile(fileName, fileNameBak)
             # The backup succeeded.
             fileNameExisted = True
-        except:
+        except IOError, Error:
             # The backup failed. This can happen if the file didn't exist before.
             fileNameExisted = False
         # write the file

src/shared.py

@@ -16,8 +16,6 @@ import sys
 import stat
 import threading
 import time
-import shutil  # used for moving the data folder and copying keys.dat
-import datetime
 import traceback
 from binascii import hexlify
 

src/throttle.py

@@ -26,8 +26,6 @@ class Throttle(object):
                     self.txLen = 0
 
     def wait(self, dataLen):
-        with self.lock:
-            self.waiting = True
         with self.lock:
             self.txLen += dataLen
             self.total += dataLen
@@ -38,8 +36,6 @@ class Throttle(object):
             if self.txLen < self.limit:
                 break
             self.timer.wait(0.2)
-        with self.lock:
-            self.waiting = False
 
     def getSpeed(self):
         self.recalculate()