Searchfield API: Changes

The following header file(s) have changed between 3.0 and 3.1

**Table 1:** aknsfld.h
Type	Class	Change
New public method	`CAknSearchField`	`void SetOldItemIndex( TInt aOldItemIndex );`
New public method	`CAknSearchField`	`TInt OldItemIndex();`

The following header file(s) have changed between 3.1 and 3.2

**Table 2:** aknsfld.h
Type	Class	Change
New public method	`CAknSearchField`	`IMPORT_C void MakeVisible( TBool aVisible );`