This function copies a variable to another (possibly existing) variable of BioticData .
The name of the variable to copy.
The name of the (possibly existing) variable insert the values in FromVariable to.
Logical: If TRUE overwrite the existing variable, if ToVariable is the name of an existing variable in the same table as FromVariable.
Logical: Only used if Overwrite is TRUE. If PreserveClass is TRUE (the default) do not convert the class of the variable given by ToVariable to the class of the variable given by FromVariable.
A BioticData object.