Rename make_ functions to _create
Implement set_cursor and set_feedback

This adds the management code to manage tablet tools lifetimes from
libinput.
It follows the suggestion made in the tablet-unstable-v2.xml to destroy
tablet_tools once all tablets that it got into contact with were removed
from the system. This is implemented via a refcount.

If a tool is *not* unique, it will be destroyed on proximity out. This
is libinput specific and mentioned in libinput docs that tools will not
be found again, so we shouldn't keep a reference to them.
Also they can't be on other tablets as well, because they cannot be
tracked.

The naming in this commit is a bit off (to not break things).
The wlr names stay the same, tablet_tool is the libinput_device with
capaiblity LIBINPUT_DEVICE_CAP_TABLET_TOOL which is more akin to
"tablet" in the tablet-unstable-v2 protocol.
The struct that corresponds to the tablet_tool in tablet-unstable-v2 is
called tablet_tool_tool, a rename should be done at some point in the
future.

screencopy: fix segfault when client supplies invalid buffer

This reverts commit a0afedcd.

Add wlr_surface.opaque_region

Unbreak xvfb

surface: replace wlr_surface_set_role_committed with wlr_surface_role

Otherwise running under Xvfb will not deliver any events. This results
in e.g. weston-info reporting a 0x0 window size (which results in all
sorts of problems).

So far we did not check for any errors

util: add wlr_ prefix to log symbols

fix: handle 32 bit time_t (or smaller)