Fixes for all of the plugins. Added a script to invoke mypy. (I'm stiiiick of .bat files. They are just broken.)

plugins/USBPrinting/USBPrinterOutputDevice.py

@@ -2,7 +2,7 @@
 # Cura is released under the terms of the AGPLv3 or higher.
 
 from .avr_isp import stk500v2, ispBase, intelHex
-import serial
+import serial   # type: ignore
 import threading
 import time
 import queue

plugins/USBPrinting/USBPrinterOutputDeviceManager.py

@@ -258,7 +258,7 @@ class USBPrinterOutputDeviceManager(QObject, OutputDevicePlugin, Extension):
     def getSerialPortList(self, only_list_usb = False):
         base_list = []
         if platform.system() == "Windows":
-            import winreg #@UnresolvedImport
+            import winreg # type: ignore @UnresolvedImport
             try:
                 key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE,"HARDWARE\\DEVICEMAP\\SERIALCOMM")
                 i = 0
@@ -277,4 +277,4 @@ class USBPrinterOutputDeviceManager(QObject, OutputDevicePlugin, Extension):
                 base_list = base_list + glob.glob("/dev/ttyUSB*") + glob.glob("/dev/ttyACM*") + glob.glob("/dev/cu.*") + glob.glob("/dev/tty.usb*") + glob.glob("/dev/rfcomm*") + glob.glob("/dev/serial/by-id/*")
         return list(base_list)
 
-    _instance = None
+    _instance = None    # type: "USBPrinterOutputDeviceManager"

plugins/USBPrinting/avr_isp/stk500v2.py

@@ -7,7 +7,7 @@ import struct
 import sys
 import time
 
-from serial import Serial
+from serial import Serial   # type: ignore
 from serial import SerialException
 from serial import SerialTimeoutException
 from UM.Logger import Logger
@@ -184,7 +184,7 @@ class Stk500v2(ispBase.IspBase):
 
 def portList():
     ret = []
-    import _winreg
+    import _winreg  # type: ignore
     key=_winreg.OpenKey(_winreg.HKEY_LOCAL_MACHINE,"HARDWARE\\DEVICEMAP\\SERIALCOMM") #@UndefinedVariable
     i=0
     while True: