-registering same system multiple times only replace pointer for callback

-added export attributes (required by windows to make DLL library, not work at now due to DMD bugs)
-interface D files to import

.gitignore

@@ -10,4 +10,8 @@ perf.data.old
 *.obj
 *.exe
 *.lib
-*.so
+*.so
+*.def
+*.lib
+*.dll
+*.exp