Bump number of workers to be the same as number of CPUs
Bump number of workers to be the same as number of CPUs

The problem is likely IO bound so in very large machines this is
probably the wrong setting.  But for most machines this should be OK.

Also fixed a bug in swrite() due to a utility function that moved to
EvalContext.

ricardog/raster-project,ricardog/raster-project,ricardog/raster-project,ricardog/raster-project,ricardog/raster-project