Memory corruption on transpose + external matrices

[dsimcha]

On Windows this just causes erratic behavior. On Linux, where glibc does some extra checking, it causes a crash with a "double free or corruption error".

import scid.matvec, scid.internal.regionallocator;

void main() {
    auto alloc = newRegionAllocator();
    auto m = ExternalMatrixView!double(3, 4, alloc);
    auto mt = eval(m.t);
}