Simplify checking of container (List/HashTable, strings) sizes

- can use 'XX.empty()' instead of 'XX.size() == 0', 'XX.size() < 1' or
  'XX.size() <= 0' or for simpler coding.
  It also has the same number of characters as '!XX.size()' and /might/ be
  more readable

- many size checking had 'XX.size() > 0', 'XX.size() != 0', or 'XX.size() >= 1'
  when a simple 'XX.size()' suffices

applications/utilities/mesh/manipulation/objToVTK/objToVTK.C

@@ -48,7 +48,7 @@ string getLine(std::ifstream& is)
     {
         std::getline(is, line);
     }
-    while((line.size() > 0) && (line[0] == '#'));
+    while (line.size() && line[0] == '#');
 
     return line;
 }