enable libmodbus quirks

[r00t-]

mbpoll, being a tool likely used for testing/debugging, should give it's users access to all possible options, without forcing them to recompile.

[r00t-]

this solves #75 and probably #39 too.
(i needed this because i have a device using address 248 ("PZEM-014/016 Energy Meter")

[r00t-]

quirks was added in stephane/libmodbus@f0db03d
two years ago.
if it's desired to support older libmodbus versions, this would have to be made conditional at compile-time.

[JesseRiemens]

Would be useful indeed! But I think this may not be behavior you want by default, for a reason?
(I'm not sure why libmodbus put it behind a function call, but they may have done it for a reason)
According to their documentation it it not compliant with the protocol, so that could be why.

I think this should be enabled by a flag, instead of having it in always.

[r00t-]

i gave my reasoning to not make it optional above, i don't think it's worth adding an option.
if one did that, one should also catch every possible error case that _could _ be prevented by enabling quirks and suggest to enable it (see #87).

but i think that's all kind of moot, as this project seems to be dead anyway.

[JesseRiemens]

Made a pr (#99 ) to add conditional quirk support.
Project may be dead but I have my local working version at least.