Adding Item Creation to SML

New type of data type:
	item	an
	
Create header fields using 
	sfsheader(an,AN,-1,1,-1,0.0001,0.0,0,0,1);
	sfshistory(an,"history field");
	sfsparams(an,"params field");

Create buffer
	sfsbuffer(an,numframes);

Access buffer
	sfsput(an,frameno,elidx,value);
	value = sfsget(an,frameno,elidx);
	sfsputs(an,frameno,elidx,string);
	string = sfsgets(an,frameno,elidx);
	an[idx] = value			- unstructured items only
	value = an[idx];

Store buffer
	sfsputitem(filename,an,numframes);
	
Load item from file
	sfsgetitem(filename,an);

