Does not handle markdown link

[zhaocai]

Test: [vim-git](https://github.com/tpope/vim-git)
Result: open-browser would try to open the whole [vim-git](https://github.com/tpope/vim-git) as a link.
Problem: the () is parsed as link with https:// ...

[tyru]

Thanks for the report.
() is valid characters in URL.
but as usual, those characters are not used for URL. removed it.

[zhaocai]

Thanks~