added operator './' (float division) and test

scanner.go

@@ -148,6 +148,8 @@ func (self *scanner) fetchNextToken() (tk *Token) {
 		case '.':
 			if next, _ := self.peek(); next >= '0' && next <= '9' {
 				tk = self.parseNumber(ch)
+			} else if next == '/' {
+				tk = self.moveOn(SymDotSlash, ch, next)
 			} else {
 				tk = self.makeToken(SymDot, ch)
 			}