MDL-20538 get rid of badly name-spaced constants from lib/questionlib.php.

Unfortunately, they are used all over the import/export code, so I cannot eliminate them completely. However, I was able to move them out of the core library.

question/format.php

@@ -27,6 +27,29 @@
 defined('MOODLE_INTERNAL') || die();
 
 
+/**#@+
+ * The core question types.
+ *
+ * These used to be in lib/questionlib.php, but are being deprecated. Copying
+ * them here to keep the import/export code working for now (there are 135
+ * references to these constants which I don't want to try to fix at the moment.)
+ */
+if (!defined('SHORTANSWER')) {
+    define("SHORTANSWER",   "shortanswer");
+    define("TRUEFALSE",     "truefalse");
+    define("MULTICHOICE",   "multichoice");
+    define("RANDOM",        "random");
+    define("MATCH",         "match");
+    define("RANDOMSAMATCH", "randomsamatch");
+    define("DESCRIPTION",   "description");
+    define("NUMERICAL",     "numerical");
+    define("MULTIANSWER",   "multianswer");
+    define("CALCULATED",    "calculated");
+    define("ESSAY",         "essay");
+}
+/**#@-*/
+
+
 /**
  * Base class for question import and export formats.
  *
@@ -697,7 +720,7 @@ class qformat_default {
             }
 
             // do not export random questions
-            if ($question->qtype==RANDOM) {
+            if ($question->qtype == 'random') {
                 continue;
             }