Moved all attributes relating to extension into a sub-element "extension"
Renamed "depends" to "dependsfileset"
Renamed "optional" to "optionalfileset"
Added "depends" sub element that are the same as "extension" sub-element
Added "option" sub element that are the same as "extension" sub-element
git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@272251 13f79535-47bb-0310-9956-ffa450edef68