Added BOOST_NO_INT64_T protection for sqrt2_pow_max 64 bit specialization

[SVN r85689]
Remove obsolete MSVC check from pragma guard

 git grep -h -B1 "^#\s*pragma once" | grep -v pragma | sort | uniq

is now clean.

[SVN r85952]
Fixes #9332

[SVN r86626]
Updated changelog with #9332

[SVN r86652]
Fixes #9338

[SVN r86748]
End-of-line normalization. Most normalization was taken care of by .gitattributes, but a few files originally committed to svn with incorrect eol tags need explicit normalization. See .gitattributes man page and extensive list discussion.
Changes for 1.56 made during Git transition:

*  Improved Doxygen generated reference and updated and fixed forward-declaration header.

*  Source breaking: Removed previously deprecated `xxx_dont_splay` functions from splay containers and removed `splay_set_base_hook` and `splay_set_member_hook`from splay containers.
Fixes #9520
Fixed documentation after removal of deprecated splay_set_xxx_hooks.
pack_options is now public, documented and tested so that it can be used by other libraries like Container, to specify new options for customizable containers.
Simplified rebalancing code extracting common operations to a local variable
Fixed copy/paste error in "cache_last" option's documentation.
Simplify splay algorithms avoiding redundant calls.
Improved floor_log2 function with intrinsics when available. Used De Brujin multiplication method otherwise.
Improved "count" for unique associative containers. Instead of calling tree's count just use find() != end() to avoid iterations as there is only one potential key.

Fixed some typos.
Implemented equal_range for unique associative containers using lower_bound_range. This might be a bit slower when comparison function is very lightweight, but shines when it's heavy as it just needs to perform a single additional comparison and a possible successor iteration.
Fixed ABI regression introduced in Boost 1.55
Optimized tree-rebalancing code to avoid redundant pointer updates.
Create first merge point for Git