NOTE: This commit does not touch the ant build system at all,
only gradle.
There are currently 23 gradle projects which require configuration,
let alone building, in order to build F-Droid. This takes a non-trivial
amount of time/memory/cpu. Additionally, it also provides difficulties
when importing the project into Android Studio - which is the IDE that
many potential contributors will be using. Finally, I have over 100mb
of data in the extern/ folder, and the support libraries require almost
every single Android SDK to be installed, which is several GB. This is
not a friendly environment to encourage people to submit merge requests.
However, I'm very mindful of the need for an open source project such
as F-Droid to be able to be built from source. So to make sure we have
the best of both worlds, I've ensured that building all dependencies
from source is still possible.
The F-Droid/libs/README.md file explains in greater detail how to
do this (i.e. "gradle -PsourceDeps build").
As much as possible, I've tried to make the binary dependencies fetched
from jcenter. However there are still libraries which either haven't
integrated required changes for F-Droid back upstream, or don't have
mavenCentral/jcenter binaries available.
Android preference fragment has been changed to the original
upstream repository. The one we had before was because upstream
hadn't merged a MR for gradfle support yet. However, that has
now been merged. This version still doesn't exist in jcenter though.
In order for libsuperuser to build from upstream, using
`gradle -PsourceDeps`, we need to include a few gradle plugins
from jcenter which are never actually used (used by upstream to
release to jcenter).
Even though support-v4 is included through jcenter, it is kept in
the libs directory, so that ./ant-prepare.sh can use it.
Update support preference fragment to newer version. There has been
bugfixes commited, so lets include them in the version we are using.
