Transceiver52M: Make GSM pulse filter internal to implementation

There is no reason expose the pulse shaping filter outside of the
signal processing calls. The main transceiver object makes no use
of the filter and there's no reason to pass it around.

Initialize the pulse shape with the signal processing library, and
maintain an internal static member like many of the other library
variables. Similarly destroy the object when the library is closed.

Signed-off-by: Thomas Tsou <tom@tsou.cc>
7 files changed