Fix: For films only consider 2D part of Bravais matrix

The whole Bravais matrix was read in, even for film calculations. But
then it overwrites dtilda, stored in the (3,3) element. This lead
to errors in the z position of atoms in films.

io/r_inpXML.F90

@@ -805,15 +805,23 @@ SUBROUTINE r_inpXML(&
          valueString = TRIM(ADJUSTL(xmlGetAttributeValue(TRIM(ADJUSTL(xPathA))//'/bravaisMatrix/row-1')))
          a1(1) = evaluateFirst(valueString)
          a1(2) = evaluateFirst(valueString)
-         a1(3) = evaluateFirst(valueString)
+         IF(.NOT.input%film) THEN
+            a1(3) = evaluateFirst(valueString)
+         END IF
          valueString = TRIM(ADJUSTL(xmlGetAttributeValue(TRIM(ADJUSTL(xPathA))//'/bravaisMatrix/row-2')))
          a2(1) = evaluateFirst(valueString)
          a2(2) = evaluateFirst(valueString)
-         a2(3) = evaluateFirst(valueString)
+         IF(.NOT.input%film) THEN
+            a2(3) = evaluateFirst(valueString)
+         END IF
          valueString = TRIM(ADJUSTL(xmlGetAttributeValue(TRIM(ADJUSTL(xPathA))//'/bravaisMatrix/row-3')))
-         a3(1) = evaluateFirst(valueString)
-         a3(2) = evaluateFirst(valueString)
-         a3(3) = evaluateFirst(valueString)
+         IF(.NOT.input%film) THEN
+            a3(1) = evaluateFirst(valueString)
+            a3(2) = evaluateFirst(valueString)
+            a3(3) = evaluateFirst(valueString)
+         ELSE
+            WRITE(*,*) 'Note: For film calculations only the upper left 2x2 part of the Bravais matrix is considered.'
+         END IF
       END IF
    END IF ! Note: Further ways to define lattices might be added later. (1D lattice,...)