Declaration of `SymbolRef` is confusing and embarrassing to percept the code easily, especially when working along with symbolic regions, values, expressions (`SVal`, `SymbolVal`, `SymbolData`, etc.). Every time it takes time to recall the correct aliasing in mind. Rename `SymbolRef` to `SymExprRef` would have a benefit.
P.S. In some files you can see bigger chunks than one-word-renaming. It is just auto-formatting changes.