Nit: free memory pointer is not padded after clone()

[ChiTimesChi]

Subtle difference between clone() and join() behavior:

join() pads the updated free memory pointer:

memview-sol/contracts/TypedMemView.sol

Lines 797 to 798 in 79a08cb

	// new pointer is old + 0x20 + the footprint of the body
	mstore(0x40, add(add(ptr, _footprint), 0x20))

While clone() does not:

memview-sol/contracts/TypedMemView.sol

Line 714 in 79a08cb

mstore(0x40, add(add(ptr, _len), 0x20)) // write new unused pointer

If a payload having length other than 32 * N bytes is cloned, this will result in the free memory pointer being not padded with a full word size. Which should not impact the library itself, but its consumers might expect the pointer to be always padded.