Add JUMPSTACK kRISC instruction

CHANGELOG.md

@@ -2911,4 +2911,4 @@ Bug fixes
 - Terminal created
 - KerboScript designed and implemented
 - VAB Part created
-- Flight stats and bindings created
+- Flight stats and bindings created

src/kOS.Safe/Compilation/Opcode.cs

@@ -87,7 +87,7 @@ public enum ByteCode :byte
         ARGBOTTOM      = 0x60,
         TESTARGBOTTOM  = 0x61,
         TESTCANCELLED  = 0x62,
-
+        JUMPSTACK      = 0x63,
 
         // Augmented bogus placeholder versions of the normal
         // opcodes: These only exist in the program temporarily
@@ -1102,6 +1102,27 @@ public override void Execute(ICpu cpu)
             DeltaInstructionPointer = Distance;
         }
     }
+
+    /// <summary>
+    /// <para>
+    /// Pops a Int32 from the stack and then unconditionally
+    /// advances the instruction pointer by it
+    /// </para>
+    /// <para></para>
+    /// <para>... dist ...</para>
+    /// </summary>
+    public class OpcodeJumpStack : Opcode
+    {
+        protected override string Name { get { return "jumpstack"; } }
+        public override ByteCode Code { get { return ByteCode.JUMPSTACK; } }
+
+        public override void Execute(ICpu cpu)
+        {
+            object popval = cpu.PopValueArgument();
+            int distance = Convert.ToInt32(popval);
+            DeltaInstructionPointer = distance;
+        }
+    }
 
     /// <summary>
     /// Most Opcode.Label fields are just string-ified numbers for their index