Names for the results of basic operations on dynSeries objects was '--NA--'. The name of the result
variables now keep track of the operations. For instance, if we have two dynSeries objects, ts1 and
ts2, respectively holding two variables 'A1' and 'B1', then:

 - the name of the variable in ts3=ts1+ts2 is 'plus(A1,B1)'
 - the name of the variable in ts3=ts1-ts2 is 'minus(A1,B1)'
 - the name of the variable in ts3=ts1*ts2 is 'multiply(A1,B1)'
 - the name of the variable in ts3=ts1/ts2 is 'divide(A1,B1)'
 - the tex name of the variable in ts3=ts1+ts2 is '(A1+B1)'
 - the tex name of the variable in ts3=ts1-ts2 is '(A1-B1)'
 - the tex name of the variable in ts3=ts1*ts2 is '(A1*B1)'
 - the tex name of the variable in ts3=ts1/ts2 is '(A1/B1)'