Problem: integer overflow when calculating sizes (may happen e.g. with very large images) (#1148)

* Problem: integer overflow when calculating sizes (may happen e.g. with very large images)
Solution: change some types from (unsigned) long to size_t

# Conflicts:
#	dlib/dnn/tensor.h

* Fix the fact that std::numeric_limits<unsigned long>::max() isn't always the same number

* Revert serialization changes

* Review fix: use long long instead of size_t

* From long to long long all the way

* Change more types to (hopefully) make the compiler happy

* Change many more types to size_t

* Change even more types to size_t

* Minor type changes

dlib/svm/linearly_independent_subset_finder_abstract.h

@@ -173,7 +173,7 @@ namespace dlib
                 - swaps *this with item
         !*/
 
-        unsigned long size (
+        size_t size (
         ) const;
         /*!
             ensures

dlib/test/object_detector.cpp

@@ -151,7 +151,7 @@ namespace
             }
         }
 
-        inline unsigned long size () const { return feat_image.size(); }
+        inline size_t size () const { return feat_image.size(); }
         inline long nr () const { return feat_image.nr(); }
         inline long nc () const { return feat_image.nc(); }
 

dlib/xml_parser/xml_parser_kernel_1.h

@@ -127,7 +127,7 @@ namespace dlib
                 bool move_next (
                 ) const { return list.move_next(); }
 
-                unsigned long size (
+                size_t size (
                 ) const { return list.size(); }
             };
 

examples/object_detector_advanced_ex.cpp

@@ -134,7 +134,7 @@ public:
         }
     }
 
-    inline unsigned long size () const { return feat_image.size(); }
+    inline size_t size () const { return feat_image.size(); }
     inline long nr () const { return feat_image.nr(); }
     inline long nc () const { return feat_image.nc(); }