(svn r2112) -Fix: ExtMidi no longer halts the game while starting a song
-Fix: Redirect stdin/stdout/stderr of the ExtMidi process to /dev/null, to prevent it from writing to the terminal
While here give the ExtMidi functions canonical names

#ifndef CALLBACK_TABLE_H
#define CALLBACK_TABLE_H

extern CommandCallback *_callback_table[];
extern const int _callback_table_count;

#endif