Fix D0> and add unit test.

Author: Molorius

.gitignore

@@ -1,6 +1,7 @@
 ulp-forth
 .vscode/
 dist/
+.DS_Store
 out.bin
 out.nonportable.S
 out.S

pkg/forth/builtin/03_double.f

@@ -41,7 +41,13 @@
 ;
 
 : D0>
-    NIP 0>
+    DUP 0< IF
+        2DROP FALSE EXIT
+    THEN
+    0> IF
+        DROP TRUE EXIT
+    THEN
+    0<>
 ;
 
 : D<>

pkg/forth/suite_test.go

@@ -1763,6 +1763,18 @@ func TestDoubleSuite(t *testing.T) {
 				T{          MIN-2INT D0< -> <TRUE>  }T
 			`,
 		},
+		{
+			name: "D0>",
+			code: `
+				T{                0. D0> -> <FALSE> }T
+				T{                1. D0> -> <TRUE>  }T
+				T{  MIN-INT        0 D0> -> <TRUE>  }T
+				T{        0  MAX-INT D0> -> <TRUE>  }T
+				T{          MAX-2INT D0> -> <TRUE>  }T
+				T{               -1. D0> -> <FALSE> }T
+				T{          MIN-2INT D0> -> <FALSE> }T
+			`,
+		},
 		{
 			name: "D0=",
 			code: `