Fix checksum (#223)

* Ensure checksum is one byte

* Bump version to 0.16.7

Author: teharris1

insteonplm/messages/extendedSend.py

@@ -157,7 +157,7 @@ def set_checksum(self):
         for i in range(1, 14):
             data_sum += self._userdata["d{:d}".format(i)]
         chksum = 0xFF - (data_sum & 0xFF) + 1
-        self._userdata["d14"] = chksum
+        self._userdata["d14"] = chksum & 0xff
 
     def set_crc(self):
         """Set Userdata[13] and Userdata[14] to the CRC value."""

setup.py

@@ -11,7 +11,7 @@ def readme():
 
 setup(
     name='insteonplm',
-    version='0.16.6',
+    version='0.16.7,
     author='David McNett',
     author_email='nugget@macnugget.org',
     url='https://github.com/nugget/python-insteonplm',