Merge branch 'master' into python3, Add pymodbus to default requirements

Author: dhoomakethu

README.md

@@ -12,7 +12,7 @@ Modbus Simulator with GUI based on modbus-tk and Pymodbus
 
     ```
     $ # Kivy depends on Cython, Install Cython before running the requirements
-    $ pip install Cython==0.25.2
+    $ pip install Cython==0.29.2
     $ pip install -r requirements
     $ # Choose Modbus Backend modbus_tk or pymodbus (default)
     $ # To install pymodbus

requirements

@@ -6,6 +6,7 @@ Kivy-Garden==0.1.4
 pygame==1.9.4
 pyglet==1.2.4
 Pygments==2.1.3
+pymodbus==2.1.0
 pyserial==3.2.1
 requests==2.12.4
-six==1.10.0
+six==1.10.0