Markdown file as internet link

See a link in case of a md file only as local link if it doesn't start with a supported protocol.
Example found was:
```
[Ansibullbot](https://github.com/ansible/ansibullbot/blob/master/ISSUE_HELP.md)
```

1 files changed, 2 insertions, 0 deletions

diff --git a/src/util.h b/src/util.h
index 31691af..a3dd6e3 100644
--- a/src/util.h
+++ b/src/util.h
@@ -453,6 +453,8 @@ bool copyFile(const QCString &src,const QCString &dest);
 QCString extractBlock(const QCString text,const QCString marker);
 int lineBlock(const QCString text,const QCString marker);
 
+bool isURL(const QCString &url);
+
 QCString correctURL(const QCString &url,const QCString &relPath);
 
 QCString processMarkup(const QCString &s);