__seguse.txt added to show _seg usage also OpenVGMFile needs to be ported to 16_snd...

__seguse.txt added to show _seg usage also OpenVGMFile needs to be ported to 16_snd.c ][ ca needs huge amounts of work and i should remember what needs to be done soon also i should reverify 16_in.c to make sure it can work with other code of id engine] going to port rest of code to borland c some time so we can use the core components of id engine here [going to add 16_us.c eventually but the debug system and CA_ PM_ and MM_ usage is priority now]