Have _compile_filters return an array of filters
Have _compile_filters return an array of filters

We need to preserve the order of --ignore-dir and --noignore-dir
directives, and the filter collection facility doesn't have a way to
do that

karenetheridge/App-Ack,openstrike/ack2,packy/ack2,gregory-nisbet/ack2,packy/ack2,h3xx/ack2,karenetheridge/App-Ack,karenetheridge/App-Ack,h3xx/ack2,gregory-nisbet/ack2,openstrike/ack2,gregory-nisbet/ack2,petdance/ack2,openstrike/ack2,karenetheridge/App-Ack,h3xx/ack2,openstrike/ack2,petdance/ack2,gregory-nisbet/ack2,gregory-nisbet/ack2,packy/ack2,h3xx/ack2,karenetheridge/App-Ack,petdance/ack2,packy/ack2,petdance/ack2,h3xx/ack2,gregory-nisbet/ack2,openstrike/ack2,h3xx/ack2,gregory-nisbet/ack2,karenetheridge/App-Ack,karenetheridge/App-Ack,openstrike/ack2,petdance/ack2,packy/ack2,petdance/ack2,openstrike/ack2,h3xx/ack2,packy/ack2,karenetheridge/App-Ack,openstrike/ack2,packy/ack2,packy/ack2,gregory-nisbet/ack2,petdance/ack2,petdance/ack2,h3xx/ack2