own functionality to calculate file checksums - close #261 git-svn-id: svn://svn.opensde.net/opensde/opensde/trunk@20154 10447126-35f2-4685-b0cf-6dd780d3921f
git-svn-id: svn://svn.opensde.net/opensde/opensde/trunk@20073 10447126-35f2-4685-b0cf-6dd780d3921f