setGainMode ignores automatic parameter

[ConnorGibbons]

Hi, while using this library I noticed that I was unable to set the gain mode via the setGainMode function.

int r = sendCommand(RTLTCP_SET_GAIN_MODE, gainMode ? 0 : 1);
I believe the issue is right there on line 438, the operation should be using the 'automatic' value instead of gainMode's.

Worth noting that gainMode is set to automatic's value at the end of the function, so a workaround is to call the function twice.

[zuckschwerdt]

Oops, keen eye. Do yo want to PR the fix or should I quickly commit the change?

[ConnorGibbons]

Hi @zuckschwerdt, opened a PR here