test box 3p3c: added coarse grid for testing, changed reference

solution.


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@8837 2fb0f335-1f38-0410-981e-8018bf24f1b0

test/boxmodels/3p3c/grids/test_3p3c.dgf

 DGF
 Interval
-0 0   % first corner 
-500 10   % second corner
-250 10   % 500 cells in x and 20 in y direction
+0 0    % first corner 
+500 10 % second corner
+250 10 % cells in x and y direction
 # 
 GridParameter
 overlap 0 

test/boxmodels/3p3c/grids/test_3p3c_coarse.dgf

+DGF
+Interval
+0 0    % first corner 
+500 10 % second corner
+40 4   % cells in x and y direction
+# 
+GridParameter
+overlap 0 
+periodic 
+closure green
+#GridParameter 
+BOUNDARYDOMAIN
+default 1    % all boundaries have id 1
+#BOUNDARYDOMAIN
+# unitcube.dgf