Remove last remnants of Seq.tostring and deprecate it
Remove redundant str(...) in print statements
Make these full Biopython deprecation warnings, not just pending.

Also remove duplicate imports
PEP8 tweaks, print functions
Remove deprecated Bio.HotRand module
Remove deprecated Bio.Search module
Remove deprecated class InterlacedSequenceIterator from SeqIO
Now testing under Python 3.4

We'll have this on the buildbot server shortly, while
Python 3.4 support on Travis-CI.org is expected soon.