Add a new option CONFIG_SCHED_TICKLESS to enable the tickless OS.  This is a work in progress but should be relatively safe since the new features are only enabled by this option (Safer but not 100% safe since it does not protect from typos and other dumb errors).

Rename up_timerinit() to up_timer_initailize(); Add prototypes for candidate interfaces for the tickless OS; Don't build existing timer initialization logic if CONFIG_SCHED_TICKLESS is defined.

NSH networking: There is now a configuration option that will bring up the network on an separate thread.  Since the network bring-up is asynchronous, there are not serial console start-up delays due to the network negotiation time.

PCM decoder: Handle errors in the PCM WAV file in a way that the Nxplayer can recover gracefully: Send and Audio Complete message.

WM8904: Add reset logic to put the part back in its initial state after playing each WAV file.  Base samles per second on frame length, not bits-per-sample.  Use a different frame length for 8-bit and 16-bit data

WM8904: Correct calculation of bitrate (I am not sure why this is correct). LR clock divisor is now a constant 32-bits per frame. Conditioned out interrupt logic; it is not being used. Also added some FLL lock interrupt/poll logic (which was subsequently disabled).

WM8904 interface enable method now returns the previous interrupt state.  Correct ordering of some WM8904: Need to provide MCLK before initializing the WM8904, not after

WM8904:  Tried disabling the SYSCLK while updating the FLL.  Didn't help but is still probably a correct change

WM8904:  Various updates to get BCLK/LRCLK correct.  Acutally worse the parent, but I think is on the right track