Move include files to srk31/ directory proper.

--HG--
rename : include/algorithm.hpp => include/srk31/algorithm.hpp
rename : include/array.hpp => include/srk31/array.hpp
rename : include/array_slice_iterator.hpp => include/srk31/array_slice_iterator.hpp
rename : include/concatenating_iterator.hpp => include/srk31/concatenating_iterator.hpp
rename : include/conjoining_iterator.hpp => include/srk31/conjoining_iterator.hpp
rename : include/downcasting_iterator.hpp => include/srk31/downcasting_iterator.hpp
rename : include/endian.hpp => include/srk31/endian.hpp
rename : include/indenting_ostream.hpp => include/srk31/indenting_ostream.hpp
rename : include/iterator_with_lens.hpp => include/srk31/iterator_with_lens.hpp
rename : include/ordinal.hpp => include/srk31/ordinal.hpp
rename : include/rotate.hpp => include/srk31/rotate.hpp
rename : include/selective_iterator.hpp => include/srk31/selective_iterator.hpp
rename : include/util.hpp => include/srk31/util.hpp