Support mouse in Vimperator popup list

[c02y]

Issue type:

• Feature request

Version:

Vimperator:	3.16.0 (created: 2017/02/01 00:55:15)
Firefox:	Mozilla/5.0 (X11; Linux i686; rv:45.0) Gecko/20100101 Firefox/45.0

Description:

When using Vimperator's commands such as b, o t and many other commands that will open a small window containing a list, I can use Tab or S-Tab to navigate the list and Enter to choose the item. But using mouse to click the item in the list directly is not supported, I think it is more convenient to use mouse here than Tab+Typing in many situations.

Expected behavior:

Support mouse in Vimperator popup list