Adapt concepts from the C++ numerics library

[wolfram77]

Consider the following enhancements. Include any functions that have not already been mentioned.

Bit manipulation

• bit_cast*
• byteswap*
• has_single_bit*
• bit_ceil*
• bit_floor*
• bit_width*
• countl_zero*
• countl_one*
• countr_zero*
• countr_one*
• popcount*
• rotl
• rotr