Adds 500 ms delay to initial registering for samples from all tuners to
feed the spectral display/waterfall. The existing approach of immediately
registering for samples was causing the airspy tuner to lockup
aperiodically. Investigation via debugger didn't show any application
thread locks ... usb master processor was continuing to service libusb
timeouts. Unable to debug internal airspy processes. Adding the delay
to startup seems to be a usable solution.
produces a significant reduction in memory usage, especially for tuners
like the airspy and hackrf that produce 10/20 MSPS sample rates. This
is observed to be around 66% reduction in peak memory usage and provides
a more stable memory utilization across time reducing stress on the
garbage collector.
Use of these reusable memory buffers will be pushed further down into
the processing chain modules to ensure we keep new object creation
to the lowest levels possible.
