fix glitch in fft.c and add scripts to display data sets without temp file

- usrp/doall: new script to directly evaluate and plot data sets
- usrp/fft.c (fft_complex): don't square the magnitude
- usrp/plscan: if an argument name has the form title=name, use "name" as
  the file name and "title" as the title

usrp/fft.c

@@ -32,7 +32,7 @@ static void fft_complex(int n, const float *re, const float *im, double *res)
 
 	for (i = 0; i != n; i++) {
 		a = hypot(out[i][0], out[i][1])/n;
-		a = a*a;
+//		a = a*a;
 		res[i] = a;
 	}
 }