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: If 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.