file_save(char* name,void* buffer,long size)
Opens the file with the given name, writes the buffer content into it,
and closes the file.
name - file name
buffer - pointer to a buffer that contains the file content.
size - the file size in bytes.
pointer to the buffer,
or NULL if the instruction failed.
This instruction is intended for external languages and thus uses
char* and long instead of STRING* and var.