Fixed testing of 128bit integer types and added staic assert that cheks for std::numeric_limits specializations, if they are required for conversion (refs #8790)

git-svn-id: http://svn.boost.org/svn/boost/trunk@85072 b8fc166d-592f-0410-95f2-cb63ce0dd405
Get rid of BOOST_LCAST_HAS_INT128 macro and use BOOST_HAS_INT128 instead (refs #8790)

git-svn-id: http://svn.boost.org/svn/boost/trunk@85073 b8fc166d-592f-0410-95f2-cb63ce0dd405
Patch from Thomas Luu for the case where Pearson's approximation goes negative.

git-svn-id: http://svn.boost.org/svn/boost/trunk@85074 b8fc166d-592f-0410-95f2-cb63ce0dd405
Don't throw exceptions from itrunc/iround if all we're doing is checking to see if the argument is an integer.
Don't propagate no-throw policies inside MPFR's itrunc/iround.
Use normal approximation to student's t quantile when the degrees of freedom is big enough.
Fixes #8837.

git-svn-id: http://svn.boost.org/svn/boost/trunk@85075 b8fc166d-592f-0410-95f2-cb63ce0dd405
Ticket 8852. Thanks Alex.

git-svn-id: http://svn.boost.org/svn/boost/trunk@85076 b8fc166d-592f-0410-95f2-cb63ce0dd405