Ensure that NT2_INSTALL_SHARE_DIR is set when used in CMake

I ended up with:

Install the project...
-- Install configuration: ""
CMake Error at cmake_install.cmake:39 (FILE):
  file cannot create directory: /tools/is_supported.  Maybe need
  administrative privileges.
Fix compile error: a user provided default ctor is required here

The clang 3.2 generated error is:

nt2/modules/test/benchmark/src/priority.cpp:70:33: error:
          default initialization of an object of const type 'const
          nt2::details::priority_booster' requires a user-provided
          default constructor
  static priority_booster const priority_booster;
                                ˆ
OSX does not define "__unix" macro, uses __APPLE__ && __MACH__ instead

See: http://sourceforge.net/p/predef/wiki/OperatingSystems/#macos
Merge pull request #437 from joker-eph/OSX

Fix a few build issues on MacOS
adding some tests to (i)divround units
boost.simd: include required headers for bitwise and/xor

Signed-off-by: Tim Blechmann <tim@klingt.org>
Fix Issue #311 - Complete support for all constants as Matlab function

Most constants are now usable through a matlab like call usign sizes.
This allows for easier initialization of matrices.
Merge pull request #438 from timblechmann/topic/fixes

boost.simd: include required headers for bitwise and/xor
better support in generate_dependencies for VERBOSE mode + fix small issue with empty (non-found) files
Add common io for unit tests.
Fix NT2_TEST_ULP_EQUAL when handling Sequence/FusionSequence hybrid types

The ulp check functions now prioritize Fusion Sequence handling
before regular Sequence handling.
Wrong include in test IO

ostream is required instead of iosfwd
Revert "Fix NT2_TEST_ULP_EQUAL when handling Sequence/FusionSequence hybrid types"

Problem arises with table which is both Sequence and FusionSequence, leading to
either requestign comaprison on container or flatten view in which info about the
failure's location is lost.
Fix ulp checking.

Properly supports recursive sequence/fusion sequence types in
ULP testing functions.
forgotten scalar floating case for adds
bad #if test in iround2even
Merge pull request #434 from MetaScale/issue_311

Provide a Matlab equivalent to every constants
fix bad usage of BOOST_SIMD_NO_XXX macros in iround
fix issue #439 missing boost/simd/sdk/config.hpp includes
clean up adds and subs for issue #421