Add support for Intxx and UIntxx to graph widget

[rangoy]

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I tried to add a variable to a graph, and it did not work as due to the filter of acceptedDatatypes in graphwidget.py

I got this message in the log;

uaclient.graphwidget - INFO - Variable cannot be added to graph because it is of type Int16 or an array')

I added the number types avaliable in Prosys Simulation server. I do not know if there might be other types too.

I think this will solve issue #85