Expands a quarterly series into a monthly one, by duplicating 3 times the quarterly values.
EXAMPLE
x=reshape([1:35],'1978q1')// ceate a quarterly tsy=q2m(x)// gives an montly ts, from 1978m1 to 2012m12 with values 1 for all months of the first quarter of year 1978, // 2 for all months of the second quarter of year 1979...