Move websearch from botton of context menu to underneath copy selection.

It seems the 'Copy Selection' button got moved between when the patch
was made and when it finally got applied. Got missed during the merge.

![](http://i.imgur.com/ncia5wx.png) vs ![](http://i.imgur.com/152dCv1.png)

[Was menu.addAction(SmallIcon("edit-copy") in the PR](https://github.com/quassel/quassel/pull/13/files#diff-509e92fe0be2c90a578793222ac75e2cL803)

[menu.insertAction(sep, act); by the time it got merged](https://github.com/quassel/quassel/commit/d30eb5039971db578ba6e777d737344187e5b02a#diff-509e92fe0be2c90a578793222ac75e2cL815)
Relabel the websearch button to 'WebSearch Selection'.

Users unfamiliar with this button might assume it means to search the
backlog rather than opening the web browser.