Add some distributions to the concept tests that were missing before.
Add skew_normal_distribution to distributions.hpp.
Fix some errors in calculating custom policies when the defaults have been changed.
Fix the errors and warnings that result from the above.
Refs #6934.
[SVN r78711]
New special functions for truncation and rounding, plus exponential integrals and zeta.
New non central distributions.
Updated equation png's so that they are all consistent.
[SVN r44091]
Made sure that if BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS is defined, then no long double overloads are actually instantiated by the tests.
[SVN r41007]
Lots of warning suppression changes.
Added new tests to verify header includes (plus fixes where these new tests failed!).
Documentation updates.
[SVN r3575]
