Many functions amaned and some new ones added.
Some additonaal checks inserted in function and simplication of code resumed up to 'ds.C'.
Functions upgraded up to 'ds.contourPlot' inclusive.
Many functions amended to accomodate the possibility to give the 'opal' through the console when there are more than one opal login object. Functions updated up to 'ds.densityGrid'.
Functions updated up to 'ds.exp' inclusive.
Functions updated up to 'ds.exp' inclusive again.

Merge branch 'agaye' of https://github.com/datashield/dsbaseclient into agaye

Conflicts:
	R/ds.asCharacter.R
	R/ds.asFactor.R
	R/ds.asNumeric.R
	R/ds.changeRefGroup.R
	R/ds.corTest.R
	R/ds.dataframe.R
	R/ds.densityGrid.R
	man/ds.asFactor.Rd
	man/ds.changeRefGroup.Rd
	man/ds.corTest.Rd
All examples verified and bug sorted up to 'ds.cov'.
Functions updated and examples checked up to 'ds.isNA' inclusive.
Functions updated and examples checked up to 'ds.isValid' inclusive.
Directory 'tests' put back to solve conflict.
Conflict solved.

Merge branch 'agaye' of https://github.com/datashield/dsbaseclient into agaye

Conflicts:
	R/ds.isNA.R
Naming changes in some functions. All updated up to 'ds.list' inclusive.
All updated up to 'ds.log' inclusive.
Merge branch 'agaye' of https://github.com/datashield/dsbaseclient into agaye
'meanByClass' and 'ds.var' updated. Two internal function added 'getPooledMean' and 'getPooledVar' to avoid calling the client functions 'ds.mean' and 'ds.var' internally with risk of the process stopping due to checks not required when computing pooled mean or variance internally.
Unwanted functions deleted. And some functions updated.
'ds.histogram' mistakenly deleted now re-introduced. Bug in 'ds.quantileMeanDS' sorted. All functions updated up to 'ds.quantileMean'.
Functions updated up to 'ds.subclass'.
Functions updated up to 'ds.subset'. New function 'ds.vectorCalc' added.
All functions checked up to 'ds.meanByClass' inclusive.