SM6FBQ / HackRF clone - History

Merge pull request #437 from gvz/master

libhackrf: counts the open devices, prevents exit if not all closed

Revert Travis to xcode 7.3 to ignore pip issue for now
- Issue to correct this is #438

Use pip2 rather than pip because it's not available with xcode 8.3

short pulses when enabling VAA to avoid a big voltage glitch

eliminated minor glitch caused by enabling a GPIO output before setting its value

Revert Travis to xcode 7.3 to ignore pip issue for now
- Issue to correct this is #438

libhackrf: counts the open devices, prevents exit if not all closed

fixes #435, osmosdr calls hackrf_exit for the last sink and the last
source. If both are in one flow graph the desctructor of the source
fails as the sink already closed the usb context.
This prevents hackrf_exit to close the context if not all devices are closed