Read input and output signals in client.Read

[d0pam1n]

This PR adds the ability to read input and output signals with the method client.Read. You can use the following variable represenations.

Input: I/E[startbyte].[bit] (e.g. I1.1, E2.1) Output: Q/A[startbyte].[bit] (e.g. Q1.1, A2.1)