Replace copy with shallow_copy, deep_copy.
Replace overlay with shallow_overlay, deep_overlay.
Significant rewrite of these functions and their semantics to update to
the note above them.
Add corresponding tests.
tl;dr is that new no longer needs to call init, calling :new() directly in user code is not allowed, properties are copied, metamethods work, and a config table is needed rather than a class to extend from, so use {extends = superclass} if you want a minimal fix
- modified functional.reduce signature; takes seed value before function now as this results in much more readable calling code
- added filter_inplace and aliased remap as map_inplace to make semantics more clear
- rewrote many functions to use numeric for as a tiny speed boost at the cost of library code readability
[modified] sequence to be compatible
