number_cast<To, From> and Named Smart Casts

number_cast is strongly typed to specific numerical conversions with options for rounding during conversions, conversion overflow checking and a high resilience to coding errors. It can be used as a generic verbose casting function, in the same manner as static_cast. Or specific commonly used conversions can be aliased to a descriptive name whose correct application has the uncluttered appearance and the syntactical flexibility of a C style cast.