First commit after creating branch, 'ds.subclass' added.
Function 'ds.subclss' completed.
Messages for user amended.
Bug sorted.
Message to user amended to include study names.
Code amended, lines referring to empty subsets removed .
Messages added for when a subset is missing in some or all the studies.
Message slightly amended.
Function 'ds.subset' amended.
'ds.subset' amended.
Added a variable 'var2sub' within the function.
Function 'ds.subset' and its helper amended.
Function amended. 'ds.dim' not ready yet.
Function 'ds.meanByClass' completed.
'ds.propMean' removed some headers amended.
'ds.var' amended to call the new server side var function 'varDS'.
Pooled and split options added to 'ds.meanByClass' and a bug sorted.
Merge of agaye branch
Fix functions renamed in dsbase
automated tests added, message formatting