Add timeout on ep.write

[CedricB31]

Hi Alex
In my application (R&S FSW over usbtmc), timeout expired during a write to the EP. That's why I added a timeout on each writing.

[SimplicityGuy]

This looks good. I wonder if this would address issues that I've seen with the R+S NRP8S power meter... Sometimes we see a timeout expired after sending some commands.

[Shivaschandra]

Hi All,
Why is variable timeout on class Instrument fixed to 1sec. In my case I use oscilloscope and it doesn't really help because, instrument has to do auto scaling of the signal and then return amplitude. If possible please add timeout as an argument.I have done it locally.