DataLayout Backing Array Dimension Checks

[jb-mackay]

Some DataLayout objects have constructors that allow for backing arrays with dimensions that don't match what one would expect given the stored types.

e.g.

FT = Float64
S = Complex{FT}
vf1 = VF{S}(Matrix{FT}, 3)
vf2 = VF{S}(ones(3, 7))

Here, vf1 generates a VF struct with a backing array of the expected size (3 x 2 as v = 3 and complex components need two elements). However, vf2 also works and creates a backing array with size 3 x 7; in this case, more than half of this stored data is inaccessible and unused.

We can add a typesize check in the bugged constructor to prevent this. The other DataLayout constructors should be reviewed for similar issues.

[charleskawczynski]

Fixed by #665.