Removed ifstream NULL comparison

In C++11, implicit conversion changed from void* to bool

snf_engine.cpp

 void TokenMatrix::Load(const char* FileName) {                                  // Initializes the token matrix by file name.
 
   ifstream MatrixFile(FileName,ios::binary);                                    // Open the file.
-  if(MatrixFile == NULL || MatrixFile.bad())                                    // If anything is wrong with the file
-    throw BadFile("TokenMatrix::Load()(MatrixFile==NULL || MatrixFile.bad())"); // then throw a bad file exception.
+  if(MatrixFile.bad())                                                          // If anything is wrong with the file
+    throw BadFile("TokenMatrix::Load() finds MatrixFile.bad()");                // then throw a bad file exception.
 
   Load(MatrixFile);                                                             // Load the matrix from the file.
   MatrixFile.close();                                                           // Be nice and clean up our file.