fix apply_visitor.
Merge pull request #11 from osyo-manga/apply_visitor_bug_fix

fix apply_visitor.
support polymorphic visitor (variant)
add static_variant_visitor
add as_variant_visitor
fix container_traits for pointer type
fix to_string for longer string
add tristate_lexicographical_compare
fix warning: shuffle_order
add range::tristate_lexicographical_compare
fix cstring, cwchar
add tristate_lexicographical_compare: delimiter version
fix README
add make_ptr_range
add range::unstable_accumulate, range::unstable_inner_product
fix recursion depth: distance
add random::make_range
fix distance
add make_ptr_range overload
fix recursion depth O(logN): some algorithms
fix algorithm
fix recursion depth: some algorithms