Change PrawnBlaster read_status to use readline instead of readlines

[carterturn]

readlines relies on timeouts, so it can be slow. See issue #145 for more details; this PR implements option 1.

[carterturn]

I have installed this version on my lab's apparatus and confirmed that transition to manual is much faster (no longer noticeable). Experiment behavior seems correct, but it would probably be good to verify that in another environment as well.

[dihm]

I'd prefer the solution used in the PrawnDO. Basically, use readline, if there is something up, then run readlines to clear out the full buffer and throw the error. A straight copy-paste of the logic used there should work.

[carterturn]

That is a good idea; I should have checked the PrawnDO code first.
Do you know if there is a reason the PrawnBlaster code has an if case for response? If response was None, I suppose the += might fail, but readline/readlines seem to return empty strings in that case.
The PrawnDO does not have this if case, so I am inclined to remove it here as well.

[dihm]

That is a good idea; I should have checked the PrawnDO code first. Do you know if there is a reason the PrawnBlaster code has an if case for response? If response was None, I suppose the += might fail, but readline/readlines seem to return empty strings in that case. The PrawnDO does not have this if case, so I am inclined to remove it here as well.

I don't know why that response check was there. Happy to remove it.

[dihm]

LGTM