ext.img_display: don't draw image when fonth/fontw is 0
ext.img_display: disable preview_images when unsupported
Merged code to manipulate version control systems

Supports git, hg and bzr.
Support for extracting metadata from version control systems

  * Makes fsobject aware of vcs.
  * Makes directory get vcs status data when loading content.
  * Adds a config option to enable/disable the vcs info feature.
Displays version control data on browser column

  * I have restructured BrowserColumn._draw_directory. Hopefully it is easier
    mantain now. Simplified horizontal space computations, etc.

  * Displays two symbols on the right of every entry, showing local status, and
    status regarding the remote vcs repo.

  * Added the necessary context to be able to change colors for individual
    symbols from the colorscheme.
Displays version control data on the status bar

Data displayed: branch, repo status and summary of last commit.
Adds config settings and documentation for the vcs feature
Added version control system related commands

Adds commands to stage, unstage changes, and to display diffs and logs using the
embedded pager.
Rebuilt manpage