ncgeodataset: fix geo{name}(indexes).data method and add "help ncgeodataset" examples
Contents.m: Add 'help nctoolbox' doc.
cdm/ncgeovariable.m: fix "help ncgeovariable.ncgeovariable"
cdm/ncgeodataset.m: fix getlondata().
Merge pull request #20 from drf5n/drf2

ncgeodataset: fix geodataset{name}(indexes).data method and add "help ncgeodata...