Added elements to the CstVec for Array processing.
Use the Array primaries when fixing domains.
Use CstStage everywhere.

This way we get the flexibility of solving constraints in an order different from the order in which the stages are listed.
Reorganized the solve function by factoring out solveStage.
Some more refactoring in the constraint solver.
lengthVar now keeps a reference to loopVar.

This is required for kicking of loop unrolling when the length variable gets resolved by the constraint solver.
Added unroll functionality to CstVecExpr and CstBddExpr.
Array values are now getting constrained and randomized.

But we need to reflect these randomized values back to the actual array elements.
Fixed parsing of foreach constraints blocks.