Comment out code that displays error information for tests.
Add rules.equalitySymmetric to the set of facts, fixing bug in Expr.dump.
Rename conjunctsReplacer to conjunctsSimplifier.
Remaining files needed for previous commit.
Minor edits.
Minor edits.
Stop logging assertion failures; they may well be caught.
Improve variable names in sample proof.
Fix some small bugs, improve display of "facts", implement rules.replaceWithT.
Get rid of problematic one-off assignment to Toy.autoAssert in tests.
Make every (original) step be its own original.
Improve some comments.
Use the math font in fact presentations ("Proof of fact x = x * 1").