implement a different threadpool behavior

    * the threadpool size now relies on the total count of checks
    * there will be core threads sized with 10th of the checks count
    * non core threads will die after 30 seconds

Signed-off-by: Robin Wittler <r.wittler@mysportgroup.de>
Merge branch 'master' into debian-squeeze

    * new upstream release
add changelog for debian-squeeze-0.2.13-1 package