It won't support GTK3 in the LXPanel. It's suggested to either
keep using the 1.4 branch or to use the systray icon once again.

The LXPanel plugin API was completely changed in version 0.7.0
without any module versioning or backwards compatibility. This
patch make the plugin work with the new version while retaining
the ability to still build for the old version (based on checking
the package version at compile time).

Since the brightness plugin merged with the battery plugin,
rename it to Power Manager Plugin. Also since we support
LXDE we'll stop calling it the Xfce Power Manager Plugin as
a LXDE plugin.

Adds support for the battery plugin to be built and used in LXDE
as the system tray icon was removed. Thanks to
https://github.com/nandhp/multiload-nandhp as it was used as a
complete example on how to easily do this. There may be a couple
things that need to be added to make this have the same
functionality as the Xfce plugin.

This patch moves some code around, mostly putting shared stuff into
power-common inside common/. It also creates a new plugin to monitor
all the batteries in one icon on the panel rather than multiple icons
inside the system tray. It also removes the power-info application
as that will be moved inside the newly reworked settings dialog.