Fixed opening of Files

Removed explicit open mode, so that auto backup/auto restart is used also
for DUMPPROJECTIONS, DUMPDERIVATIVES and DUMPFORCES. Regtests has been added
with backup files.

I also removed some unnecessary c_str().

regtest/basic/rt1/bck.0.der2.reference

+fake file just to test backup

regtest/basic/rt1/der2

+fake file just to test backup

regtest/basic/rt18/bck.0.projections.reference

+fake file just to test backup

regtest/basic/rt18/projections

+fake file just to test backup

regtest/basic/rt8/bck.0.ff.reference

+fake file just to test backup

regtest/basic/rt8/ff

+fake file just to test backup

src/bias/MetaD.cpp

@@ -475,8 +475,7 @@ isFirstStep(true)
 
 // open hills file for writing
   hillsOfile_.link(*this);
-  if(plumed.getRestart()) hillsOfile_.open(ifilesnames[mw_id_],"aw");
-  else hillsOfile_.open(ifilesnames[mw_id_]);
+  hillsOfile_.open(ifilesnames[mw_id_]);
   if(fmt.length()>0) hillsOfile_.fmtField(fmt);
   hillsOfile_.addConstantField("multivariate");
   hillsOfile_.setHeavyFlush();

src/generic/DumpAtoms.cpp

@@ -153,7 +153,7 @@ DumpAtoms::DumpAtoms(const ActionOptions&ao):
 
   checkRead();
   of.link(*this);
-  of.open(file.c_str());
+  of.open(file);
   log.printf("  printing the following atoms in %s :", unitname.c_str() );
   for(unsigned i=0;i<atoms.size();++i) log.printf(" %d",atoms[i].serial() );
   log.printf("\n");

src/generic/DumpDerivatives.cpp

@@ -91,7 +91,7 @@ fmt("%15.10f")
   parse("FMT",fmt);
   fmt=" "+fmt;
   of.link(*this);
-  of.open(file,"wa");
+  of.open(file);
   log.printf("  on file %s\n",file.c_str());
   log.printf("  with format %s\n",fmt.c_str());
   unsigned nargs=getNumberOfArguments();

src/generic/DumpForces.cpp

@@ -87,7 +87,7 @@ ActionWithArguments(ao)
   parse("FILE",file);
   if( file.length()==0 ) error("name of file was not specified");
   of.link(*this);
-  of.open(file,"wa");
+  of.open(file);
   log.printf("  on file %s\n",file.c_str());
   if( getNumberOfArguments()==0 ) error("no arguments have been specified");
   checkRead();

src/generic/DumpProjections.cpp

@@ -75,7 +75,7 @@ fmt("%15.10f")
   if( file.length()==0 ) error("filename not specified");
   parse("FMT",fmt);
   fmt=" "+fmt;
-  of.open(file.c_str(),"wa");
+  of.open(file);
   log.printf("  on file %s\n",file.c_str());
   log.printf("  with format %s\n",fmt.c_str());
   checkRead();

src/generic/Print.cpp

@@ -101,7 +101,7 @@ rotate(0)
   ofile.link(*this);
   parse("FILE",file);
   if(file.length()>0){
-    ofile.open(file.c_str());
+    ofile.open(file);
     log.printf("  on file %s\n",file.c_str());
   } else {
     log.printf("  on plumed log file\n");