attempt to fix travis build failure
erase_if and tests, protect against accidental nested binds, try to fix travis-ci, fixes #62
misc clean-up, add yield_from for simpler range comprehensions
works with libc++
tests passing with gcc-4.9.1+
cont::stable_sort
cont::take and cont::drop and tests
cont::drop_while and cont::take_while and tests
Merge branch 'master' into dev