Add gamma-control wayland protocol

protocol/gamma-control.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="gamma_control">
+
+    <copyright>
+        Copyright © 2015 Giulio camuffo
+
+        Permission to use, copy, modify, distribute, and sell this
+        software and its documentation for any purpose is hereby granted
+        without fee, provided that the above copyright notice appear in
+        all copies and that both that copyright notice and this permission
+        notice appear in supporting documentation, and that the name of
+        the copyright holders not be used in advertising or publicity
+        pertaining to distribution of the software without specific,
+        written prior permission.  The copyright holders make no
+        representations about the suitability of this software for any
+        purpose.  It is provided "as is" without express or implied
+        warranty.
+
+        THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+        SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+        FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+        SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+        WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+        AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+        ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+        THIS SOFTWARE.
+    </copyright>
+
+    <interface name="gamma_control_manager" version="1">
+        <request name="destroy" type="destructor"/>
+
+        <request name="get_gamma_control">
+            <arg name="id" type="new_id" interface="gamma_control"/>
+            <arg name="output" type="object" interface="wl_output"/>
+        </request>
+    </interface>
+
+    <interface name="gamma_control" version="1">
+        <enum name="error">
+            <entry name="invalid_gamma" value="0"/>
+        </enum>
+
+        <request name="destroy" type="destructor"/>
+
+        <request name="set_gamma">
+            <arg name="red" type="array"/>
+            <arg name="green" type="array"/>
+            <arg name="blue" type="array"/>
+        </request>
+
+        <request name="reset_gamma"/>
+
+        <event name="gamma_size">
+            <arg name="size" type="uint"/>
+        </event>
+    </interface>
+</protocol>