i18n and graceful sorting for year values 'in press', 'submitted' and 'accepted'

The sorting mechanism relied solely on strcmp before, which yielded a more or less random result.
It is now possible to define an order as long as the strings in the bibtex file are given in their standard English form.
In output though, the strings are internationalised.

bibtexbrowser.php

@@ -122,6 +122,9 @@ function bibtexbrowser_configure($key, $value) {
 @define('READLINE_LIMIT',1024);
 @define('Q_YEAR', 'year');
 @define('Q_YEAR_PAGE', 'year_page');
+@define('Q_YEAR_INPRESS', 'in press');
+@define('Q_YEAR_ACCEPTED', 'accepted');
+@define('Q_YEAR_SUBMITTED', 'submitted');
 @define('Q_FILE', 'bib');
 @define('Q_AUTHOR', 'author');
 @define('Q_AUTHOR_PAGE', 'author_page');
@@ -1376,6 +1379,9 @@ class BibEntry {
 
   /** Returns the year of this entry? */
   function getYear() {
+    return __(strtolower($this->getField('year')));
+  }
+  function getYearRaw() {
     return $this->getField('year');
   }
 
@@ -1728,7 +1734,47 @@ function compare_bib_entry_by_mtime($a, $b)
  */
 function compare_bib_entry_by_year($a, $b)
 {
-  return -strcmp($a->getYear(),$b->getYear());
+  $yearA = (int) $a->getYear();
+  $yearB = (int) $b->getYear();
+
+  if ($yearA === 0) {
+    switch (strtolower($a->getYearRaw())) {
+      case Q_YEAR_INPRESS:
+        $yearA = PHP_INT_MAX;
+	break;
+      case Q_YEAR_ACCEPTED:
+        $yearA = PHP_INT_MAX - 1;
+	break;
+      case Q_YEAR_SUBMITTED:
+        $yearA = PHP_INT_MAX - 2;
+	break;
+      default:
+        $yearA = PHP_INT_MAX - 3;
+    }
+  }
+
+  if ($yearB === 0) {
+    switch (strtolower($b->getYearRaw())) {
+      case 'in press':
+        $yearB = PHP_INT_MAX;
+	break;
+      case 'accepted':
+        $yearB = PHP_INT_MAX - 1;
+	break;
+      case 'submitted':
+        $yearB = PHP_INT_MAX - 2;
+	break;
+      default:
+        $yearB = PHP_INT_MAX - 3;
+    }
+  }
+
+  if ($yearA === $yearB)
+    return 0;
+  else if ($yearA > $yearB)
+    return -1;
+  else
+    return 1;
 }
 
 /** compares two instances of BibEntry by title