traits: new trait to recognize load arguments

A trait to look at an arbitrary number of types. If the type combination
is one that matches a load constructor / function call then value is
true, false otherwise.

Signed-off-by: Matthias Kretz <kretz@kde.org>
simd_array: fix load offsets

After IndexesFromZero is fixed, the load tests failed. The load ctor and
load function had to adjust the memory pointer for the offsets of the
sub simd_array objects.

refs #613

Signed-off-by: Matthias Kretz <kretz@kde.org>
simd_array: converting loads work fine

Signed-off-by: Matthias Kretz <kretz@kde.org>
simd_array: fix store offsets

like for loads, the memory pointer needs to be adjusted for the offset
of the first sub simd_array.

refs #613

Signed-off-by: Matthias Kretz <kretz@kde.org>