DATV demod: compile for 16 bit Rx DSP only. Cosmetic changes

Merge branch 'dev'

PlutoSDR output: fixed plugin installation path

FileSource: fixed initialization of do apply settings flag

Updated missing documentation for SSB and WFM audio UDP output

DSD demod: use lower cutoff for optional audio high pass filter

DSD demod: gcc7 warnings fixes

Web API: updated examples documentation

SSB: updated documentation

Windows build fixes