Initial check-in of icontext work.

win/share/tile2bmp.c

@@ -360,3 +360,10 @@ pixel (*pixels)[TILE_X];
         }
     }
 }
+
+/* nhassert_failed is called when an nhassert's condition is false */
+void nhassert_failed(const char * exp, const char * file, int line)
+{
+    Fprintf(stderr, "NHASSERT(%s) in '%s' at line %d\n", exp, file, line);
+    exit(EXIT_FAILURE);
+}

win/win32/winhack.c

@@ -97,6 +97,7 @@ WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine,
 
     win10_init();
 
+    icontext_init();
     sys_early_init();
 
     /* init applicatio structure */