fleece headers listed in iOS framework module map files are not correct

The current Module map file (valid for lithium) needs update for new fleece headers (See below). For example, Base.h should be FLBase.h. Also, I'm not sure if it needs to declare all header or just top level headers (Maybe top level is enough) - Need to verify.

module Fleece {

  header "Base.h"

  header "Fleece.h"

  header "FLSlice.h"

  header "Fleece+CoreFoundation.h"

}