fix exit status: several executables reported success (0) on failure or vice versa

Two bug patterns fixed across src/*.cpp:

- musrfit, musrview, any2many, addRun, musrFT, musrt0: a local
  success/ok/isGood flag was tracked and an error printed, but the
  function fell through to an unconditional `return PMUSR_SUCCESS;`
  at the end instead of propagating the failure.
- msr2data, msr2msr: the success path returned a nonzero code (1)
  instead of 0.

Also propagate previously-ignored return codes to the process exit
status in dump_header (format-dispatch functions), musrRootValidation
(schema validation / consistency checks), and write_musrRoot_runHeader
(FillFolder failure).

src/write_musrRoot_runHeader.cpp

@@ -245,8 +245,11 @@ int main(int argc, char *argv[])
   // root file header related things
   TFolder *runHeader = new TFolder("RunHeader", "MusrRoot Run Header Info");
 
-  if (header->FillFolder(runHeader)) {
+  bool success = header->FillFolder(runHeader);
+  if (success) {
     runHeader->Write();
+  } else {
+    std::cerr << std::endl << "**ERROR** couldn't fill the MusrRoot run header folder." << std::endl;
   }
 
   f->Close();
@@ -255,5 +258,8 @@ int main(int argc, char *argv[])
   delete f;
   delete header;
 
+  if (!success)
+    return -1;
+
   return 0;
 }