Modernize numeric

[saki7]

Supersedes boostorg/spirit#830

Part of #4

This PR modernizes numeric and numeric_utils components.

• Add constexpr to almost everywhere
• Use if constexpr in static branches
• Use iterator/sentinel pair, avoid unconstrained typename Iterator
• Add noexcept to primitive operations
• Use <cstdint> instead of Boost version
• Use <type_traits> instead of Boost version