Replicates all needed state between expanded functions

commit 5e6f06cf59
Author: Aaron Gutierrez <gutierrez.aaron.m@gmail.com>
Date:   Thu May 11 15:42:11 2017 -0400

    Fixed issue with aliasing local variables

    ISPC++ now produces valid code, or an appropriate error message, for all
    of my test cases.

commit bfe723e1b7
Author: Aaron Gutierrez <gutierrez.aaron.m@gmail.com>
Date:   Thu May 11 03:09:38 2017 -0400

    Actually copy the AST.

    Type replacement works except for function parameters.

commit f65b3e6300
Author: Aaron Gutierrez <gutierrez.aaron.m@gmail.com>
Date:   Thu May 11 01:19:50 2017 -0400

    [WIP] Remove cases for ForeachStmt and SymbolExpr

commit 2e28640860
Merge: 6a91c5d d020107
Author: Aaron Gutierrez <gutierrez.aaron.m@gmail.com>
Date:   Wed May 10 23:13:40 2017 -0400

    Merge branch 'master' into copy_ast

commit 6a91c5d5ac
Author: Aaron Gutierrez <gutierrez.aaron.m@gmail.com>
Date:   Wed May 10 11:11:39 2017 -0400

    Attempt to replicate AST when expanding polytypes

stmt.h

@@ -70,6 +70,7 @@ public:
     // Stmts don't have anything to do here.
     virtual Stmt *Optimize();
     virtual Stmt *TypeCheck() = 0;
+    Stmt *Copy();
     Stmt *ReplacePolyType(const PolyType *polyType, const Type *replacement);
 };
 
@@ -283,7 +284,6 @@ public:
     void Print(int indent) const;
 
     Stmt *TypeCheck();
-    Stmt *ReplacePolyType(const PolyType *from, const Type *to);
     int EstimateCost() const;
 
     std::vector<Symbol *> dimVariables;