xfce4-power-manager: update to 1.3.0, supporting upower-0.99

(cherry picked from commit 2027dcc4f9444bf52e92556531e550c08b094918)
libxfce4util: minor update 4.10.0 -> 4.10.1

(cherry picked from commit 5c72dac5487df7c230eea7a4559db54ce32106ef)
xfce4-appfinder: update 4.9.4 -> 4.10.1

(cherry picked from commit 8aa892489e5b1dfa0fce3a64ea16c6286cd02232)
libav: maintenance updates of all three branches

(cherry picked from commit c61c7e7313fdc5e402b0f71e0430ae3367a7c55c)
thunderbird: major update 17.* -> 31.0

- To fix build problems, I refactored the build process
  according to Mozilla recommendations.
- 31.0 should become the next ESR branch (31 released today).

CC @nbp @edolstra

(cherry picked from commit adc2edd5cf524239690b5cf49779a11fd2eb061b)