tests: add expect_protocol_error function

This function checks if a particular protocol error came in wire.
It's usefull in the cases where we hitherto used FAIL_TEST.
The problem with FAIL_TEST is that *any* assert will pass the test,
but we want only some asserts to pass the test (i. e. we don't
want the test to pass when it, for example, can't connect to display).
FAIL_TESTs are good only for sanity testing.

The expect_protocol_error allows us to turn all FAIL_TESTs to TESTs
as will be introduced in following patches.

v2: fixed white-space error and a mistake in comment

Reviewed-by: Bryce Harrington <b.harrington@samsung.com>
Reviewed-by: Pekka Paalanen <ppaalanen@gmail.com>
tests: add frame_callback_wait_nofail

With expect_protocol_error, we need a possibility to wait for a frame
without aborting the test when wl_display_dispatch returns -1;
This patch adds function frame_callback_wait_nofail that only
returns 1 or 0 (instead of aborting on error).

Reviewed-by: Pekka Paalanen <ppaalanen@gmail.com>
tests: use expect_protocol_error in tests

Turn FAIL_TESTs to TESTs. FAIL_TESTs are bad...

Reviewed-by: Pekka Paalanen <ppaalanen@gmail.com>
tablets: Add XML for wl_tablet and wl_tablet_manager
tablet: Add very basic motion support into weston
tablet: add support for tablet motion in libtoytoolkit
tablet: Add demo application for tablets

This is just a hacked version of clickdot that responds to tablet events
instead of cursor events
tablet: add set_cursor request to wl_tablet