Add sqrt instruction

vm/opcode.go

@@ -68,6 +68,10 @@ const (
 	OpRetT          = OpReturnIfTrue
 	OpReturnIfFalse = 0x00000802
 	OpRetF          = OpReturnIfFalse
+
+	OpSquareRoot = 0x00000900
+	OpSqRt       = OpSquareRoot
+	OpSqrt       = OpSquareRoot
 )
 
 type OperandNumericType int
@@ -118,4 +122,6 @@ var OperandsByOpCode = map[OpCodeType][]OperandNumericType{
 	OpRet:  []OperandNumericType{},
 	OpRetT: []OperandNumericType{},
 	OpRetF: []OperandNumericType{},
+
+	OpSqrt: []OperandNumericType{OperandReference},
 }