Move Nikhar Agrawal's Bernoulli code into mainstream Boost.
Fix namespace used for atomic operations.
Commit test case.
Refactor into class-based details, and split big tables off into new header.
Move unchecked_bernoulli_b2n over to new header and add to tests.
Consist input parameters for Bessel/Airy zeros.
Use atomic enumeration member from std, not boost.
Include header bernoulli.h.
Merge branch 'bernoulli-numbers' of https://github.com/boostorg/math into bernoulli-numbers

Conflicts:
	include/boost/math/special_functions/bernoulli.hpp
Enable tangent numbers.
Fix several error handling issues.
Merge branch 'bernoulli-numbers' of https://github.com/boostorg/math into bernoulli-numbers

Conflicts:
	include/boost/math/special_functions/detail/bernoulli_details.hpp
Fix gcc compiler failures
Fix GCC test failure.
Fix buggy overflow check.
Add B2n overflow test.
Add tangent numbers overflow test.
Hook up the concept checks.
Fix issues raised from the regression tests: some using declaration in the Bessel code, and some changed assumptions in the airy-zeros.
Change use of non-portable "int" to "boost::int32_t".
Make parameters const consistent.
Add support for UDT's not convertible from long long.
Added gamma file that uses Bernoulli implementation from gsoc work. The bernoulli using gamma function is currently called using gamma_imp_bernoulli(). Changes need to be further made.
changed tgamma using bernoulli to mimic previous lanczos implementation for z<=-20