Context-specific completer options. Option refactoring.

New review
Owner: dougkearns
Hopefully the changeset hash will actually be linked this time. If
not, it's the tip of the testing branch, presumably r4161.
I've been meaning to do this for a while. It allows case matching,
sorting, and auto completion options to be assigned on a per context
basis, with fine grained control. It also adds builtin regex support
to options since it's used fairly extensively. There are definitely
other options that would benefit from the regexlist type, if I can
dig them up. The interface (and perhaps the doc wording) is the only
place I'm really ambivalent.

--HG--
branch : testing

common/locale/en-US/various.xml

@@ -17,16 +17,27 @@
     <tags>:beep</tags>
     <spec>:beep</spec>
     <description>
-        <p>Play a system beep.</p>
+        <p>
+            Play a system beep. This should not be used for any purpose other
+            than testing the visual bell.
+        </p>
     </description>
 </item>
 
 
 <item>
-    <tags><![CDATA[<C-l> CTRL-L :redr :redraw]]></tags>
-    <spec>:redr<oa>aw</oa></spec>
+    <tags>:contexts</tags>
+    <spec>:contexts <a>ex-command</a></spec>
     <description>
-        <p>Redraws the screen. Useful to update the screen halfway executing a script or function.</p>
+        <p>
+            Lists the completion contexts used during the completion of its
+            arguments. These context names are used in options such as
+            <o>autocomplete</o> and <o>wildcase</o>. Note that completion must
+            be triggered in order for this command to be effective, so if
+            autocompletion is not active, you'll need to press the
+            <k name="Tab"/> key at least once. You should also be aware that
+            this command is only useful from the commandline.
+        </p>
     </description>
 </item>
 
@@ -46,6 +57,15 @@
 </item>
 
 
+<item>
+    <tags><![CDATA[<C-l> CTRL-L :redr :redraw]]></tags>
+    <spec>:redr<oa>aw</oa></spec>
+    <description>
+        <p>Redraws the screen. Useful to update the screen halfway executing a script or function.</p>
+    </description>
+</item>
+
+
 <item>
     <tags>:run :! :!cmd</tags>
     <spec>:!<a>cmd</a></spec>