-Wclass-memaccess warning should be in -Wextra, not -Wall

[Soul Studios]

Simply because a struct has a constructor does not mean it isn't a 
viable target/source for use with memcpy/memmove/memset.
Having benchmarked the alternatives memcpy/memmove/memset definitely 
makes a difference in various scenarios.
The bypass of littering code with needless reinterpret_cast<void *>'s is 
fugly.
Members which are invariants should of course be noted, but anyone using 
memset/cpy/move probably knows this.
Please discuss this annoyance. I would prefer this be moved into Extra, 
as this is less commonly used.