Re-work completions: extend engine wrapper to handle prefixes.

This commit contains the bulk og the material changes for which the
previous commits established the basis.

1) Add a general framework for detecting query prefixes in search URLs,
adding them to query sent to the completion engine, and stripping them
from the resulting suggestions.  This allows the user to have a
search engine...

   j: http://www.google.com/search?q=javascript+%s Javascript

and have the prefix "javascript" included (automatically) in queries
sent to completion engines, which results in substantially better
suggestions.

2) Re-work completion for Google Maps in a simpler form.

1 files changed, 5 insertions, 2 deletions

diff --git a/pages/completion_engines.coffee b/pages/completion_engines.coffee
index d744b3b3..790f2968 100644
--- a/pages/completion_engines.coffee
+++ b/pages/completion_engines.coffee
@@ -11,12 +11,15 @@ DomUtils.documentReady ->
     engine = new engine
     html.push "<h4>#{engine.constructor.name}</h4>\n"
     html.push "<div class=\"engine\">"
+    if engine.example.explanation
+      html.push "<p>#{engine.example.explanation}</p>"
     if engine.regexps
+      html.push "<p>"
+      html.push "Regular expression#{if 1 < engine.regexps.length then 's' else ''}:"
       html.push "<pre>"
       html.push "#{cleanUpRegexp re}\n" for re in engine.regexps
       html.push "</pre>"
-    if engine.prefix
-      html.push "<p>This uses the general Google completion engine, but adds the prefix \"<tt>#{engine.prefix.trim()}</tt>\" to the query.</p>"
+      html.push "</p>"
     if engine.example.searchUrl and engine.example.keyword
       engine.example.description ||= engine.constructor.name
       html.push "<p>"