Altered DenseSet and IndependentElementSet to record ref<Expr> involved

This is important for future changes to IndependentSolver::
getInitialValues() so that an incoming constraint can be broken
down into its smallest possible parts.  Each of these individual
parts may then be solved for and then the solutions to each piece
combined to create a final answer.

Finally, several fields which had previously been private are now
public to facilitate the smaller solutions being combined into a
larger solution.

0 files changed, 0 insertions, 0 deletions