new attributes ignoremissingbuildfiles and genericantfile
genericantfile allows to run the same build file with different base dirs
it is not compulsory any more to set the attribute target to quote quote to run the default target
PR: 18715
Submitted by: Andreas Ames (Andreas dot Ames at tenovis dot com)


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@274600 13f79535-47bb-0310-9956-ffa450edef68