Fix bug in C0Projection

This fixes a bug in the C0Projection module of FieldConvert related to the order in which the operations are performed. It is not necessary to perform a BwdTrans at the beginning (since the phys array is already available), but it should be done after the projection in order to update the phys values.

This bug does not cause problems when the output is another .fld file, but when the output is a .vtu file the original solution is being exported.