Extend AstVisitor to cover WhileDoStmt/DoWhileStmt/ForLoop.  Update the Dump Routines to provide initial printers for these.
Tweak
Merge pull request #807 from noakesmichael/Visitor

Extend While/For loops to support Visitor pattern

1) Extend WhileDoStmt, DoWhileStmt, ForLoop to support the AstVisitor pattern.

2) Update AstVisitor to know about WhileDoStmt, DoWhileStmt, ForLoop

3) Extend the three debugging "AstDump" routines to provide preliminary logging for these nodes.
I will revisit these when the internal representation for the new nodes stabilizes.


Compiled: STD clang/darwin, STD gcc/linux64, LLVM gcc/linux64
Testing:     Minimal.  This code is not executed by any regression tests
Review:    None