corrections in cpp promotion
added make_safe_literal
separated integers from other types
dropped example91
updated CMakeLists.txt and Jamfile.v2 accordingly
improved support for safe_literals
corrected errors in less_than and equal which were failing to detect possible runtime failures.
simplified pseudo partial specialization for checked_result_operations
Turns out that these changes should also better position us to handle other underlying types - but we're not there yet.
Added example for composition with other types - example boost rational and boost multi precision
Added performance test using boost multi precision
Many other small corrections
Making way for checked_float, checked_money, etc
a) factoring checked into checked_integer etc.
b) moved some tests from test_z to official tests
c) added test_rational which tests interoperability with boost::rational
d) moved safe_range to safe_integer_range
before this change, it would get instantiated by is_convertible<T, safe<U>> for any type T which created a syntax error.
This problem appears with using rational<safe<int>> but passes tests now.
Switched casting operators back to implicit. Having it explicit makes it safe types more unwieldy to use and breaks some examples.
