new XML implementation does not read external field parameters properly

As reported by Thomas Brumme Jun-Ho Lee from Korea Institute for Advanced Study, Seoul found a bug when he wanted to use the gate-implementation, but the bug is actually also there for using the external electric field via tefield = .true. / dipfield = .true.

It seems that the new XML implementation is not reading all input parameters correctly - when the code is compile with the -D__OLDXML flag, everything works as intended.

I tested this with the QE v.6.2 from 26. Jan 2018 compiled with GNU Fortran (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18). Taking the dipole_example of PP. With the old XML format, the potential plotted via "plot_num=11" includes the dipole correction but not in the new XML format. (Note that one needs to change the run_example slightly otherwise the potential is not plotted; adding a

mv avg.dat ni+co.vpot-z mv avg.dat water.vpot-z

at line 186 and 344, respectively.)

The scf run itself works without problems, also restarting. I didn't have the time yet to check where the error occurs, but it seems that it is only there in the pp.x run.