Introduce ParamForLoop as a thin veneer on BlockStmt
ParamForLoop: Refactor the constructor
Convert ParamForLoop to inherit from LoopStmt
Allow this test to fail again.

For other's sanity, allow this test to continue to fail on cygwin until we fix
it to be more portable and look into whether qio makes similar assumptions.
Merge pull request #988 from lydia-duncan/allowQioTestToFailAgain

Allow this test to fail again.

For other's sanity, allow this test to continue to fail on cygwin until we fix
it to be more portable and look into whether qio makes similar assumptions.
Merge pull request #989 from noakesmichael/param-for-loop-0

Introduce the statement ParamForLoop

This is the remaining looping AST node that relies on loop state within BlockStmt.  Introduce a new AST node for this type of loop that inherits directly from LoopStmt.

1) Introduce a simple version of ParamForLoop as a direct decedent of BlockStmt

2) Add a "factory" method on the class ParamForLoop to support the parser/builder.

3) Migrate ParamForLoop from a direct dependence on BlockStmt to a direct dependence on LoopStmt.

Compiled: STD clang/darwin, STD gcc/linux64, LLVM gcc/linux64
Tested: paratest --verify
Review: none