Minibar: make it possible to configure a list of preferred grammars

A preferred grammar is selected when a user visits the Minibar for the
first time. (Like before, Minibar remembers the selected grammar for future
visits.)

A preferred list of grammars can be specified in config.js in the .../minibar
directory on the server, e.g. like this:

  preferred_grammars=["/grammars/Foods.pgf","/grammars/ResourceDemo.pgf"]

The first available grammar from the list is used.

src/www/minibar/about.html

@@ -243,12 +243,22 @@ Some implementation details:
       the minibar. The rest of the documentation is displayed when you press
       the <b>More info</b> button (or the <b>i</b> button). The documentation
       can contain HTML markup. Blank lines are treated as paragraph breaks.
+  <li>[Added 2019-11-21] It is now possible to configure a list of preferred
+      grammars.
+      A preferred grammar is selected when a user visits Minibar for the
+      first time. (Like before, Minibar remembers the selected grammar for
+      future visits.)
+      <p>
+      A preferred list of grammars can be specified in <code>config.js</code>
+      in the <code>…/minibar</code> directory on the server, e.g. like this:
+      <pre>  preferred_grammars=["/grammars/Foods.pgf","/grammars/ResourceDemo.pgf"]</pre>
+      The first available grammar from the list is used.
 </ul>
 </main>
 <footer>
 <hr>
 <div class=modtime><small>
-<!-- hhmts start -->Last modified: Mon Aug  5 15:22:46 CEST 2019 <!-- hhmts end -->
+<!-- hhmts start -->Last modified: Thu Nov 21 14:23:59 CET 2019 <!-- hhmts end -->
 </small></div>
 <address>
 <a href="http://www.cse.chalmers.se/~hallgren/">Thomas Hallgren</a>

src/www/minibar/minibar.js

@@ -181,7 +181,15 @@ Minibar.prototype.show_grammarlist=function(dir,grammar_names,dir_count) {
 	    if(last_grammar && elem(last_grammar,t.grammars))
 		grammar0=last_grammar;
 	}
+	var pgs=t.options.preferred_grammars
+	if(!grammar0 && pgs)
+	    for(var i in pgs)
+		if(elem(pgs[i],t.grammars)) {
+		    grammar0=pgs[i]
+		    break
+		}
 	if(!grammar0) grammar0=t.grammars[0];
+	//console.log("grammar0=",grammar0)
 	t.grammar_menu.value=grammar0;
 	t.select_grammar(grammar0);
     }

src/www/minibar/minibar_online.js

@@ -21,6 +21,9 @@ var minibar_options= {
     try_google: true
 }
 
+if(window.preferred_grammars)
+    minibar_options.preferred_grammars=preferred_grammars
+
 if(/^\?\/(tmp|grammars)\//.test(location.search)) {
     var args=decodeURIComponent(location.search.substr(1)).split(" ")
     if(args[0]) online_options.grammars_url=args[0];