[Refactoring] Remove unnecessary isVarDeclaration() call
[Refactoring] Rename makeInvariant to makeImmutable
[Refactoring] Improve parser

And fix parser bug inout+const --> const
[bugfix] Normalize inout deduction
Support inout const type & fix issue 6930
fix IFTI for inout const
fix TypeFunction::iswild
++wild(1) & runnable/structlit.d
++wild(2) & runnable/structlit.d
Relax unique constructor with Expression::isUniqData()
+Add new Rebindable test case