pep8/pyflakes compliance
reset warnings filter after use
remove UnusedImport from setup.py
whitespace nit
unittest binpacked terminal warning
introduce .strip() and .strip_seqs()

the former is better used as a replacement for .strip() in text wrapping
functions, so that spaces containing sequences are equivalent to u'' for
"empty line" or "drop whitespace" evaluation.

very simply, T.length(S) == len(T.strip_seqs())