small fix in case of grain_ids are provided as input

Signed-off-by: Wolfgang Ludwig <wolfgang.ludwig@esrf.fr>

5_reconstruction/gtSetupReconstruction.m

@@ -150,6 +150,10 @@ if isempty(conf.grain_ids)
     first = 1;
     last  = sample.phases{phaseID}.getNumberOfGrains();
     list = [first : last];
+else
+    first = 1;
+    last  = 1;
+    list  = conf.grain_ids;
 end