Adjacent markup sections result in incorrect ANSI escape sequences

For example, `new Text("@|red,bg(white) (c) 2017|@@|underline VALUE2|@").toString()` resulting in missing closing ANSI escape characters.

Actual value vs. expected value:

```
[31m[47m(c) 2017[49m[39m[0m[4mVALUE2   //actual
[31m[47m(c) 2017[49m[39m[0m[4mVALUE2[24m[0m   //expected
```