Fix issue #92, throw an XPathException not an XProcException because …

…Saxon catches the former and not the latter

src/com/xmlcalabash/util/XProcURIResolver.java

@@ -257,7 +257,7 @@ public Reader resolve(URI uri, String s, Configuration configuration) throws XPa
             InputStream stream = conn.getInputStream();
             return new InputStreamReader(stream);
         } catch (Exception e) {
-            throw new XProcException(e);
+            throw new XPathException(e);
         }
     }
 }