Investigate use of lgTxPulse for pulsing clock pin

[endail]

Currently, the clock pin is pulsed with two GPIO write calls through the lg library:

https://github.com/endail/hx711/blob/master/src/HX711.cpp#L88
https://github.com/endail/hx711/blob/master/src/HX711.cpp#L97

Both call lgGpioWrite through the Utility class. But lg also has a lgTxPulse function.

I am wondering if using lgTxPulse to provide a single pulse to the HX711's clock pin may be more efficient than the two lgGpioWrite calls. If it is, it may also help to avoid the 60us power down issue.