Improved assembler

src/asm/x64/Call.go

@@ -0,0 +1,10 @@
+package x64
+
+import "io"
+
+// Call places the return address on the top of the stack and continues
+// program flow at the new address. The address is relative to the next instruction.
+func Call(w io.ByteWriter, address uint32) {
+	w.WriteByte(0xe8)
+	appendUint32(w, address)
+}