build: require libxwiimote >= 2

We need the new MP helpers so require libxwiimote >= 2.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
doc: fix website links

xwiimote website is at github-pages, fix all links to it.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
build: use xz tarballs

bz2 is deprecated, use xz.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Bump version to 0.4

New xf86-input-xwiimote release.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>