AST-1086 Pass spectral window via DPInfo

Maik Nijhuisrequested to merge
ast-1086-pass-spectral-window-via-dpinfo into master

Also rename two DPInfo::set() overloads to DPInfo::setChannels(). Also set number of channels in DPInfo::setChannels().

Edited by Maik Nijhuis

Merge request reports