Post seventh draft of the proposal.

Reword parts of the Motivation & Scope, Standard Impact, and Design
Decision sections.

Add new class template as a transformation trait to change a given
type to a (multidimensional) array type of some given extents.
Remove said transformation trait parts from "array," including
removing "array_t."

Change some template non-type parameters of "unsigned" to "size_t."
Move the variadic template ellipsis of formal parameters from the
parameter to the "typename"/type.

Move the creation function templates to their own subsection.
Clarify semantics of "make_array."  Correct "static_cast" within
definition of "reshape_array."

Tweak date.