* Optimise clearing by adding `nullptr` overload. This overload means
`Callback(NULL)` or `Callback(0)` will no longer work; users must
use `Callback(nullptr)` or `Callback()`.
* Optimise clearing by not clearing storage - increases code size of
comparison, but that is extremely rare.
* Reduce ROM used by trivial functors - share copy/destroy code.
* Config option to force trivial functors - major ROM saving by
eliminating the "operations" table.
* Config option to eliminate comparison altogether - minor ROM saving by
eliminating zero padding.
* Conform more to `std::function` API.
Updated EMAC memory manager to use libservice nsdynmemlib
for EMAC memory buffers. Located the nsdynmemlib buffer heap
to DMA safe memory bank on LPCxx boards. Optimized placement of
static variables on EMAC test environment for LPCxx boards to
maximize available memory.
Kevin Bracey
David Lin
Mika Leppänen