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
