Added flags for elemental pressures

src/VTK/input_of_outputs.txt

-0  ! output u field
-1  ! output v field
-0  ! output w field
+0  ! output u scalar field 
+0  ! output v scalar field 
+0  ! output w scalar field 
+1  ! output velocity vectors 
+1  ! output pre-isostasy velocity vectors
 0  ! output disp=sqrt(u**2+v**2+w**2) field
-1  ! output pressure field
+1  ! output nodal pressure field 
+1  ! output raw elemental pressure field 
+1  ! output smooth elemental pressure field 
 0  ! output temperature field
-1  ! output e2d field
+1  ! output e2d field at elements 
+1  ! output e2d field at nodes
 0  ! output refinement criterion field
 1  ! output strain field
 0  ! output lsf's
@@ -13,4 +18,4 @@
 0  ! output_ps             (-> compressive.vtk)
 0  ! output_cubes          (-> cubes.vtk)
 1  ! output_rivers         (-> rivers.vtk)
-0  ! output_regular        (-> regular.vtk)
+0  ! output_regular        (-> regular.vtk)
\ No newline at end of file