Replace with terms and types

Let's set up some definitions to start:

.lib> builtins.merge

x = 1
y = 2

structural type X = One Nat
structural type Y = Two Nat Nat

.> add

Test that replace works with terms

.> replace x y
.> view x

Test that replace works with types

.> replace X Y
.> find
.> view.patch patch
.> view X

Try with a type/term mismatch

.> replace X x

.> replace y Y

Try with missing references

.> replace X NOPE

.> replace y nope

.> replace nope X

.> replace nope y

.> replace nope nope