Test wavefunction restart file functionality

The CP2K regression tester should detect issues like #2679

tests/QS/regtest-wfn-restart/H2O-wfn-restart-check.inp

@@ -0,0 +1,51 @@
+&GLOBAL
+ PREFERRED_DIAG_LIBRARY ScaLAPACK
+ PRINT_LEVEL low
+ PROJECT H2O-wfn-restart-check
+ RUN_TYPE energy
+&END GLOBAL
+
+&FORCE_EVAL
+ METHOD Quickstep
+ &DFT
+  BASIS_SET_FILE_NAME BASIS_SET
+  POTENTIAL_FILE_NAME POTENTIAL
+  &MGRID
+   CUTOFF 280
+  &END MGRID
+  &QS
+   EPS_DEFAULT 1.0E-10
+  &END QS
+  &SCF
+   EPS_SCF 1.0E-6
+   SCF_GUESS restart
+   &PRINT
+    &RESTART
+     BACKUP_COPIES 0
+    &END RESTART
+   &END PRINT
+  &END SCF
+  &XC
+   &XC_FUNCTIONAL Pade
+   &END XC_FUNCTIONAL
+  &END XC
+ &END DFT
+ &SUBSYS
+  &CELL
+   ABC  5.0  5.0  5.0
+  &END CELL
+  &COORD
+   O   0.000000    0.000000   -0.065587
+   H   0.000000   -0.757136    0.520545
+   H   0.000000    0.757136    0.520545
+  &END COORD
+  &KIND H
+   BASIS_SET DZV-GTH-PADE
+   POTENTIAL GTH-PADE-q1
+  &END KIND
+  &KIND O
+   BASIS_SET DZVP-GTH-PADE
+   POTENTIAL GTH-PADE-q6
+  &END KIND
+ &END SUBSYS
+&END FORCE_EVAL

tests/QS/regtest-wfn-restart/TEST_FILES

@@ -0,0 +1,7 @@
+# runs are executed in the same order as in this file
+# the second field tells which test should be run in order to compare with the last available output
+# e.g. 0 means do not compare anything, running is enough
+#      1 compares the last total energy in the file
+#      for details see cp2k/tools/do_regtest
+H2O-wfn-restart-check.inp                              1      8e-14             -17.152160148865224
+#EOF

tests/TEST_DIRS

@@ -3,6 +3,7 @@
 # Directories have been reordered according the execution time needed for a gfortran pdbg run using 2 MPI tasks
 # in case a new directory is added just add it at the top of the list..
 # the order will be regularly checked and modified...
+QS/regtest-wfn-restart
 QS/regtest-dcdft-force                                      libint libxc
 QS/regtest-dcdft-stress                                     libint libxc
 QS/regtest-ec-stress                                        libint libxc