docs: Use "Cogl" not "COGL" in Cogl API reference

Cogl isn't an acronym so we should use "Cogl" instead of "COGL" in
our documentation.

doc/HACKING

@@ -18,7 +18,7 @@ General notes and rules on clutter core hacking;
  - Properties should always be in floating point (never fixed point).
    The preferred precision is double for angles, and single precision
    for size and position -- especially if they have to be passed down
-   to COGL.
+   to Cogl.
 
  - Properties should use pixels whenever is possible. Dimensional and
    positional properties can also use ClutterParamSpecUnits to define
@@ -41,11 +41,11 @@ General notes and rules on clutter core hacking;
  - Private, non-static functions must begin with an underscore and
    be declared inside clutter-private.h.
 
- - Don't add direct GL calls but add API to COGL (both GL and GL|ES
+ - Don't add direct GL calls but add API to Cogl (both GL and GL|ES
    versions if possible).
 
  - Use the CLUTTER_NOTE() macro for debug statements in Clutter, and
-   the COGL_NOTE() macro for debug statements in COGL. If necessary,
+   the COGL_NOTE() macro for debug statements in Cogl. If necessary,
    add a value inside ClutterDebugFlags or CoglDebugFlags to specify
    the debug section.
 

doc/reference/clutter/running-clutter.xml

@@ -66,7 +66,7 @@
         <varlistentry>
           <term>COGL_DEBUG</term>
           <listitem>
-            <para>Enables debugging modes for COGL.</para>
+            <para>Enables debugging modes for Cogl.</para>
           </listitem>
         </varlistentry>
       </variablelist>
@@ -130,11 +130,11 @@
         <varlistentry>
           <term>--cogl-debug=FLAGS</term>
           <listitem><para>Equivalent of COGL_DEBUG. Sets FLAGS as the
-          COGL debugging flags.</para></listitem>
+          Cogl debugging flags.</para></listitem>
         </varlistentry>
         <varlistentry>
           <term>--cogl-no-debug=FLAGS</term>
-          <listitem><para>Unsets FLAGS from the COGL debugging
+          <listitem><para>Unsets FLAGS from the Cogl debugging
           flags.</para></listitem>
         </varlistentry>
         <varlistentry>

doc/reference/clutter/subclassing-ClutterActor.xml

@@ -385,16 +385,15 @@ foo_actor_allocate (ClutterActor           *actor,
     <title>Painting and picking</title>
 
     <para>The <classname>ClutterActor</classname>::paint() method should be
-    overridden if the actor needs to control its drawing process, either by
-    using the Clutter GL and GLES abstraction library (COGL) or by directly
-    using the GL or GLES API.</para>
+    overridden if the actor needs to control its drawing process, by
+    painting other child actors or drawing with the Cogl 3D graphics
+    API.</para>
 
     <example id="simple-actor-paint-example">
       <title>Paint implementation of a simple actor</title>
       <para>In this example, the <classname>FooActor</classname>
       implementation of the paint() virtual function is drawing a rectangle
-      with rounded corners with a custom color. The COGL API is used, to
-      allow portability between GL and GLES platforms.</para>
+      with rounded corners with a custom color using the Cogl API.</para>
       <programlisting>
 static void
 foo_actor_paint (ClutterActor *actor)

doc/reference/cogl/cogl-docs.xml.in

@@ -6,8 +6,8 @@
 <book id="index" xmlns:xi="http://www.w3.org/2003/XInclude">
 
   <bookinfo>
-    <title>COGL Reference Manual</title>
-    <releaseinfo>for COGL &version;</releaseinfo>
+    <title>Cogl Reference Manual</title>
+    <releaseinfo>for Cogl &version;</releaseinfo>
 
     <copyright>
       <year>2008</year>
@@ -45,12 +45,12 @@
   </bookinfo>
 
   <chapter>
-    <title>COGL - GL Abstraction API</title>
+    <title>Cogl - GL Abstraction API</title>
 
     <section id="cogl-intro">
-      <title>About COGL</title>
+      <title>About Cogl</title>
 
-      <para>COGL is a low level OpenGL abstraction library developed for (and
+      <para>Cogl is a low level OpenGL abstraction library developed for (and
       part of) Clutter. It is used primarily by Clutter to provide a common
       rendering API that works transparently across OpenGL >=1.4,
       OpenGL ES 1.1 and OpenGL ES 2.0.</para>
@@ -75,12 +75,12 @@
   </chapter>
 
   <chapter>
-    <title>COGL experimental API</title>
+    <title>Cogl experimental API</title>
 
     <section id="cogl-experimental">
       <title>About the experimental API</title>
 
-      <para>COGL has some experimental API developers are welcomed to play
+      <para>Cogl has some experimental API developers are welcomed to play
       with. The main drawback when using those is that there is no API
       stability guarantee, functions flagged as experimental could be changed
       or removed in future versions of the library. To use this experimental