fixed some compiler warnings

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402351

dlib/gui_core/gui_core_kernel_1.cpp

@@ -1528,10 +1528,10 @@ namespace dlib
         bool undecorated 
     ) :
         has_been_destroyed(false),
-        wm(gui_core_kernel_1_globals::window_table.get_mutex()),
         prevx(-1),
         prevy(-1),
-        prev_state(0)
+        prev_state(0),
+        wm(gui_core_kernel_1_globals::window_table.get_mutex())
     {
         DLIB_ASSERT(!(undecorated == true && resizable == true),
             "\tbase_window::base_window()"

dlib/gui_core/gui_core_kernel_1.h

@@ -178,7 +178,7 @@ namespace dlib
         // this is a copy of the last inputs we sent to the on_mouse_move() event.
         long prevx;
         long prevy;
-        long prev_state;
+        unsigned long prev_state;
 
     protected:
         const rmutex& wm;

dlib/svm/kkmeans.h

@@ -271,7 +271,7 @@ namespace dlib
         // pick the first sample as one of the centers
         centers.push_back(samples[0]);
 
-        const long best_idx = samples.size() - samples.size()*percentile - 1;
+        const long best_idx = static_cast<long>(samples.size() - samples.size()*percentile - 1);
 
         // pick the next center
         for (long i = 0; i < num_centers-1; ++i)