* Was not exiting with non-zero exit code when the build failed.
  * Fix the error reporting so that the entire exception chain is reported.
  * Only print out stack traces when in verbose or debug mode.
* Wrap all exceptions thrown during task initialisation and execution with
  a general 'task failed' exception.
* Another <property> testcase.


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@271802 13f79535-47bb-0310-9956-ffa450edef68

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@271669 13f79535-47bb-0310-9956-ffa450edef68

* No longer implements Configurable, uses a set() method instead.

* The property value can be included as the text content of
  the <property> element.

* Added test-cases.

* Added some alternative executeTarget() methods to
  AbstractProjectTest, to expect a particular set of log messages,
  or a particular failure.


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@271567 13f79535-47bb-0310-9956-ffa450edef68

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@271459 13f79535-47bb-0310-9956-ffa450edef68