Revert "cdm/ncgeodataset.m: Add ncgeodataset{name}.mdata(...) parsing."

This reverts commit 1ba04d4f580387099bb02e9b503404755c3f27cf.
Revert "cdm/ncgeodataset.m: Fix ncgeodataset{name}.data(...) and ncgeodataset{name}.grid(...) parsing."

This reverts commit 7975a47d7b83975e85938db0b48f86a1094428b2.
It didn't need fixing like this, since this syntax is used in demo 11:

    ncgeodataset{varname}(matlabIndexingRanges).data % get data with matlab indexed subset
    ncgeodataset{varname}(matlabIndexingRanges).grid % get grid_interop with matlab indexed subset
cdm/ncgeodataset: update comments to reflect ncgeodatasert{varname}(matlabIndexes).method syntax.