plugins/fmcomms2_adv: Add FMCOMMS2 Advanced Plugin

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
FFT: Now that we are doing complex FFT, make sure we set the axis on the negative side
FMCOMMS2_ADVANCED: Clean up warning on target from glade file

Signed-off-by: Robin Getz <robin.getz@analog.com>
SAVE DATA: Don't keep adding the file name extension over and over