New 4 words register datatypes

[papipano]

I found your EasyModbus written in python and I think is a very good work! In my case I need some more datatypes because in energy measures we have registers as 4 words. Furthermore when I tried to read Input registers it gave me an error because it calls a unexistent function "read_analog"; I modified it with "execute_read_order" and now it works. Thank you very much for your nice work.