Added regtest for RESTART

regtest/rt10-restart/COLVAR

+#! FIELDS time mu1 vol md.bias
+ 0.000000  1.163 127.933  0.000
+ 0.050000  1.131 127.933  0.950
+ 0.100000  1.098 127.933  1.759
+ 0.150000  1.080 127.933  2.578
+ 0.200000  1.087 127.933  3.651

regtest/rt10-restart/COLVAR.reference

+#! FIELDS time mu1 vol md.bias
+ 0.000000  1.163 127.933  0.000
+ 0.050000  1.131 127.933  0.950
+ 0.100000  1.098 127.933  1.759
+ 0.150000  1.080 127.933  2.578
+ 0.200000  1.087 127.933  3.651
+#! FIELDS time mu1 vol md.bias
+ 0.000000  1.163 127.933  4.223
+ 0.050000  1.131 127.933  5.638
+ 0.100000  1.098 127.933  6.497
+ 0.150000  1.080 127.933  7.153
+ 0.200000  1.087 127.933  8.302

regtest/rt10-restart/HILLS

+#! FIELDS time mu1 vol sigma_mu1 sigma_vol height biasf
+#! SET multivariate false
+                      0      1.162646040831079       127.932640011072                    0.1                    0.2                      1                      1
+                   0.05      1.130546273059004       127.932640011072                    0.1                    0.2                      1                      1
+                    0.1      1.097928292824707       127.932640011072                    0.1                    0.2                      1                      1
+                   0.15      1.080244153391634       127.932640011072                    0.1                    0.2                      1                      1
+                    0.2      1.086854650075657       127.932640011072                    0.1                    0.2                      1                      1

regtest/rt10-restart/HILLS.reference

+#! FIELDS time mu1 vol sigma_mu1 sigma_vol height biasf
+#! SET multivariate false
+                      0      1.162646040831079       127.932640011072                    0.1                    0.2                      1                      1
+                   0.05      1.130546273059004       127.932640011072                    0.1                    0.2                      1                      1
+                    0.1      1.097928292824707       127.932640011072                    0.1                    0.2                      1                      1
+                   0.15      1.080244153391634       127.932640011072                    0.1                    0.2                      1                      1
+                    0.2      1.086854650075657       127.932640011072                    0.1                    0.2                      1                      1
+#! FIELDS time mu1 vol sigma_mu1 sigma_vol height biasf
+#! SET multivariate false
+                      0      1.162646040831079       127.932640011072                    0.1                    0.2                      1                      1
+                   0.05      1.130546273059004       127.932640011072                    0.1                    0.2                      1                      1
+                    0.1      1.097928292824707       127.932640011072                    0.1                    0.2                      1                      1
+                   0.15      1.080244153391634       127.932640011072                    0.1                    0.2                      1                      1
+                    0.2      1.086854650075657       127.932640011072                    0.1                    0.2                      1                      1

regtest/rt10-restart/Makefile

+../scripts/test.make
\ No newline at end of file

regtest/rt10-restart/config

+type=driver
+# this is to test a different name
+arg="--plumed plumed.dat --stride 10 --timestep 0.005 --ixyz trajectory.xyz --dump-forces forces --dump-forces-fmt=%10.6f
+  --box 5.0388,5.0388,5.0388"
+extra_files="../trajectories/trajectory.xyz"

regtest/rt10-restart/plumed.dat

+RESTART
+mu1: DISTANCE ATOMS=1,10
+vol: VOLUME 
+
+METAD ARG=mu1,vol SIGMA=0.1,0.2 HEIGHT=1.0 PACE=10 LABEL=md
+
+PRINT ...
+  STRIDE=1
+  ARG=mu1,vol,md.bias 
+  FILE=COLVAR FMT=%6.3f
+... PRINT
+
+FLUSH STRIDE=100
+
+ENDPLUMED
+