Update to wip/vimb to vimb-2.7.

Changes:
- extended the syntax for :set commands.
  Like vim, vimb supports the following :set flavors: :set+=val, :set-=val and
  :set^=val. These works for strings, numbers and even lists. So you can now
  easily add or remove a customer header by something like :set header+=DNT=1,
  without retyping the headers you have defined before.
- Soup Webcaching.
  Vimb supports no caching of some page data on disk, to make pages load
  faster. The maximum used cache size can be configured by the new setting
  maximum-cache-size which is by default set to 2000kB. To disable the caching
  this config should be set to 0.
- CTRL-A and CTRL-X commands like in vim.
  These commands allow to increment the last number of the current opened URL.
  This allows really efficient access to pages with pagers. These commands can
  also be prefixed by a number to page in larger steps.
- input CTRL-O command.
  Allow to run normal mode command in input mode with CTRL-O. This allows to
  yank selected text within form fields by pressing CTRL-O Y or to zoom the
  page like CTRL-O 2zi
- made more of the webkit setting configurable through vimb
- simplified the logic for the bookmark handling in vimb

Fixes:
- Fixed little memory leak in prev- nextpattern validation
- Fixed window resizing in GTK3 Builds if there are large URIs shown in status
  bar
- Fixed mode switching bug on translate.google.com
- avoid to start download if the server responds with a none http success code
- according to pentadactyl, vimb keeps the pass through mode until the user
  types ESC