Make local run of the selection BE test easier

One big strain when running the selection Be test locally is the big amount of data needed - testvectors and reference files amount to approx. 70GB. So, for a full run using locally stored testvectors, one needs about 140GB of disk space (as the produced codec output has the same size than the references). To omit that, two thingss can be implemented:

• compare against the MD5 checksum instead of against the actual reference vector
• delete the created test output if no errors were found for a testcase

Both of these behaviours will not be the default and have to be passed explicitly.