Log Message:
Update to 0.20

Release notes:
## Version 0.20 (March 10, 2014)
_New features_
  - Mouse actions now support multiple buttons, by Marcin Mikołajczyk.
  - Non supported monitors are ignored in configuration files (see
    [issue #139]), by Adam Vogt.

_Bug fixes_
  - `Disk` monitor now ignores non-existent devices (Reto Hablützel).
  - `Weather` is now non-blocking and doesn't use curl (Ben Boeckel).
  - Fix for `Memory` monitor in 3.14 kernels (Ben Boeckel).
  - Fix for infinite loops in `AutoMPD` ([issue #76], [issue #111]).
  - More robust AC readings in `BatteryP`.
  - Fix for `Top` monitor's readings for processes whose name contains
    blanks.
  - Fixes for geometry computation on multihead (Dmitry Malikov).
  - Fixes for missing XDG configuration (Thiago Negri and James McCoy,
    see [issue #133]).
  - Compatibility with latest `directory` (1.2.0.2).

[issue #76]: https://github.com/jaor/xmobar/issues/76
[issue #111]: https://github.com/jaor/xmobar/issues/111
[issue #133]: https://github.com/jaor/xmobar/issues/133
[issue #139]: https://github.com/jaor/xmobar/issues/133