Crash if static files don't have none as the reduction method

[uramirez8707]

The following table

 "atmos_static",       -1,  "hours", 1, "days", "time",
 "dynamics",       "lat",      "lat",   "atmos_static", "all", .true., "none", 2

will result in the following error message:

Exception: file atmos_static is a static file, but the variable: lat is using average as its reduction method. The reduction method (6th column) should be none for a variables in a static file!