Angle quotes again :)
*Created by: huapeng01016*
With 0.17.3, the following angle quotes are not handled ideally
```
Source: "<<test>>abcd<</test1>>"
Flexmark:
<p>«test»abcd<</test1>></p>
Pegdown:
<p>«test»abcd«/test1»</p>
Source: <<test>>abcd<<:test1>>"
Flexmark:
<p>«test»abcd<<:test1>></p>
Pegdown:
<p>«test»abcd«:test1»</p>
```
issue