minor code improvements for the obj code

- make use of range for loops
- make use of empty() method for the std::vector
- removed unnecessary std::string initialization
- use ' ' instead of " " for the find methods (should be "faster")
- simplified some function
- make use of emplace_back instead of push_back (should be "faster")
- other small changes

code/Obj/ObjFileParser.h

@@ -80,7 +80,7 @@ public:
     /// @brief  Constructor with data array.
     ObjFileParser( IOStreamBuffer<char> &streamBuffer, const std::string &modelName, IOSystem* io, ProgressHandler* progress, const std::string &originalObjFileName);
     /// @brief  Destructor
-    ~ObjFileParser();
+    ~ObjFileParser() = default;
     /// @brief  If you want to load in-core data.
     void setBuffer( std::vector<char> &buffer );
     /// @brief  Model getter.