add taken, taken_while adaptors.
add dropped_while
add dropped adaptor.
plan update.
add outdirected adaptor.
add single range.
add single range example.
tab fix.
add iteration range.
equal implementation, forward_traversal to single_traversal.
add regular function. this function use lambda in range adaptor.
indirect_functor is supported to C++03.
fix duplicate include.
add directory_range, split_at.
rename macro in indirect_functor.
add split_at example.
add regular operator.
update copyright.
add regular operator to original adaptors(filtered, transformed, replaced_if).
add element access(front, back, at), and elements, elements_key adaptor.
add test by BBv2.