TST: add few more rudimentary tests for Regex to complete its coverage
ENH: FilterReader - use the set methods (improve coverage), test getters, use os.path.join
ENH: per original discussion, and changes which followed, better not to ignore absent failregex -- all filters (but included common) should have it
BF(2.4): remove use of "with" for python 2.4 for now (since we list it as supported)
BF(2.4): omit date patterns containing %f (.subsec) for Python before 2.5
Merge pull request #522 from yarikoptic/master

TST/BF: basic changes to beef up coverage a tiny bit + restore compatibility with python2.4 (since we still claim to support it)