Keep the selected view mode when typing a new URL in the ViewFile page

Otherwise, when interested in viewing `Link List` for example, each time
you typed a new URL, `Parsed Sentences` view mode was selected as
default and you had to selected again the view mode you are insterested
in.

htroot/ViewFile.html

@@ -77,6 +77,7 @@ function updatepage(str) {
     <h2>View URL Content</h2>
 
     <form method="get" action="ViewFile.html" id="searchform" accept-charset="ascii" onkeyup="xmlhttpPost(); return false;">
+      <input type="hidden" name="viewMode" value="#[viewModeValue]#" />
       <fieldset><legend>Get URL Viewer</legend>
         <dl>
           <dt>URL:</dt>

htroot/ViewFile.java

@@ -89,6 +89,7 @@ public class ViewFile {
         prop.put("topmenu", sb.getConfigBool("publicTopmenu", true) ? 1 : 0);
         prop.put("moar", 0);
         prop.put("viewMode", VIEW_MODE_NO_TEXT);
+        prop.put("viewModeValue", "");
         prop.putHTML("error_words", "");
         prop.put("error_vMode-sentences", "1");
         prop.put("error", "1");
@@ -118,6 +119,7 @@ public class ViewFile {
         final boolean showSnippet = post.get("show", "").equals("Show Snippet");
         final String viewMode = showSnippet ? "sentences" : post.get("viewMode", "sentences");
         prop.put("error_vMode-" + viewMode, "1");
+        prop.put("viewModeValue", viewMode);
         
         DigestURL url = null;
         String descr = "";