Short: new efun copy()
Date: 981229
Type: Feature
State: Done - implemented in 3.2.6-dev.61.

the efun

  mixed copy(mixed data, bool all = false)

creates and returns a value copy of data for mappings and arrays,
and returns data for everything else.

mappings and arrays are value copys (like data+({})), and if all is true,
all containing mappings and arrays are copied as well.

This efun would then replace copy_mapping(), too.