adding hints about presetdef/macrodef to the errors. Now that I am using them, they are the main source of this error :)

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@276159 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/UnknownElement.java

@@ -456,19 +456,22 @@ public class UnknownElement extends Task {
             + " - You have misspelt '" + elementName + "'." + lSep
             + "   Fix: check your spelling." + lSep
             + " - The task needs an external JAR file to execute" + lSep
-            + "   and this is not found at the right place in the classpath." + lSep
+            + "     and this is not found at the right place in the classpath." + lSep
             + "   Fix: check the documentation for dependencies." + lSep
             + "   Fix: declare the task." + lSep
             + " - The task is an Ant optional task and optional.jar is absent" + lSep
             + "   Fix: look for optional.jar in ANT_HOME/lib, download if needed" + lSep
             + " - The task was not built into optional.jar as dependent"  + lSep
-            + "   libraries were not found at build time." + lSep
+            + "     libraries were not found at build time." + lSep
             + "   Fix: look in the JAR to verify, then rebuild with the needed" + lSep
             + "   libraries, or download a release version from apache.org" + lSep
             + " - The build file was written for a later version of Ant" + lSep
             + "   Fix: upgrade to at least the latest release version of Ant" + lSep
             + " - The task is not an Ant core or optional task " + lSep
-            + "   and needs to be declared using <taskdef>." + lSep
+            + "     and needs to be declared using <taskdef>." + lSep
+            + " - You are attempting to use a task defined using " + lSep
+            + "    <presetdef> or <macrodef> but have spelt wrong or not " + lSep
+            + "   defined it at the point of use" + lSep
             + lSep
             + "Remember that for JAR files to be visible to Ant tasks implemented" + lSep
             + "in ANT_HOME/lib, the files must be in the same directory or on the" + lSep