[gradsusr] linear trend in grads

[Roberto Mera]

Hi. I've been trying to calculate the linear trend for a number of 
variables. The tregr and sregr functions do not allow for "time" as one 
of the variables. I'd like to be able to draw a map of the linear trend 
over a set number of years. I've seen that a lot of the questions people 
have usually deal with x-y plots and not actual grids.

Any suggestions are welcome.

Robert