tablet-shell: Remove

The tablet-shell is unmaintained and unused.  It is currently
dead-weight and a burden when we make changes to weston.  Let's
drop it for now, we can pull it out of git if we find a need for it later.

protocol/Makefile.am

@@ -1,7 +1,6 @@
 protocol_sources =				\
 	desktop-shell.xml			\
 	screenshooter.xml			\
-	tablet-shell.xml			\
 	xserver.xml				\
 	text.xml				\
 	input-method.xml			\

protocol/tablet-shell.xml

@@ -1,40 +0,0 @@
-<protocol name="tablet">
-
-  <interface name="tablet_shell" version="1">
-    <request name="set_lockscreen">
-      <arg name="surface" type="object" interface="wl_surface"/>
-    </request>
-
-    <request name="set_switcher">
-      <arg name="surface" type="object" interface="wl_surface"/>
-    </request>
-
-    <request name="set_homescreen">
-      <arg name="surface" type="object" interface="wl_surface"/>
-    </request>
-
-    <request name="show_grid">
-      <arg name="surface" type="object" interface="wl_surface"/>
-    </request>
-
-    <request name="show_panels">
-      <arg name="surface" type="object" interface="wl_surface"/>
-    </request>
-
-    <request name="create_client">
-      <arg name="id" type="new_id" interface="tablet_client"/>
-      <arg name="name" type="string"/>
-      <arg name="fd" type="fd"/>
-    </request>
-
-    <event name="show_lockscreen"/>
-    <event name="show_switcher"/>
-    <event name="hide_switcher"/>
-  </interface>
-
-  <interface name="tablet_client" version="1">
-    <request name="destroy" type="destructor"/>
-    <request name="activate"/>
-  </interface>
-
-</protocol>