Signed-off-by: Maciek Borzecki <maciek.borzecki@gmail.com>

Travis host images are quite outdated, so the builds will now use containers
instead. By default there's a build for Arch Linux (using base/archlinux:latest
image) and Fedora (using official fedora:latest).

Builds are done using extra/travis-build script.

This prevents a protocol handler to be fired more than once.

Add make target 'run-gdb' that will automatically start gdb with
G_MESSAGES_DEBUG=all and G_DEBUG=fatal-criticals environment variables.

Otherwise debugging with G_DEBUG=fatal-criticals is not possible.

Cleanup device signals handling. Fix a problem with duplicated signals from
Device which were a result of same signal callback being registered multiple
times.

indicated is communication with device is possible

Patched gio-2.0 VAPI files are no longer needed.

Signed-off-by: Maciek Borzecki <maciek.borzecki@gmail.com>

Implement mousepad plugin handler. The input in realized through AT-SPI.

Use Socket.create_socket_source() as it works for both TCP and UDP
sockets, but also does not use GDatagramBased interface, thus should
allow building on systems with older GLib versions.