[LIB-178] Added CshInterpolationItem type.
[LIB-178] Added CshInterpolationItem type.

chdinh/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,LorenzE/mne-cpp,chdinh/mne-cpp,chdinh/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp,LorenzE/mne-cpp,LorenzE/mne-cpp,mne-tools/mne-cpp,chdinh/mne-cpp,LorenzE/mne-cpp,mne-tools/mne-cpp,chdinh/mne-cpp