Update Lucre community project

And add minimization

Author: EugeneFlesselle

community-build/community-projects/Lucre

@@ -0,0 +1,15 @@
+
+trait Txn[T]
+trait Expr[X <: Txn[X], +Y]
+trait BinOp[T, Repr[X <: Txn[X]] <: Expr[X, T]]
+
+trait IntObj[T] extends Expr[T, Int]
+trait IntBinOp extends BinOp[Int, IntObj]
+object IntEq extends IntBinOp
+
+object Test:
+  val r: BinOp[?, ?] = IntEq : BinOp[Int, IntObj] // error: Required: BinOp[?, ?[X] <: Expr[X, BinOp[?, ?]#T]]
+  // We would need the second wildcard to "depend" on the 1st one,
+  // e.g. have SomeBinop[?] where `type SomeBinop[X] = BinOp[X, ? <: [Y] =>> Expr[Y, X]]`,
+  // but this is an instance of an unreducible application of higher-kinded type to a wildcard argument.
+  // Also note there would be no error if we made BinOp covariant in T.